Arrow between BTrees

Question

I have a BTree made in TiKz in which I add a new element. Then the BTree has to be transformed. I would like to make it look like the example picture:

But I don't know how to achieve that? EDIT: I want to insert the arrow where the Rightarrow is in the example below

\documentclass[11pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[german]{babel}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}

\usepackage{tikz}
\usepackage{tikz-cd}
\usetikzlibrary{shapes}

\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\begin{document}

\begin{tikzpicture}
\tikzstyle{bplus}=[
    rectangle split, 
    rectangle split horizontal,
    rectangle split parts = 3, 
    draw
]
\tikzstyle{every node}=[bplus]
\tikzstyle{level 1}=[sibling distance=20mm]
\node {5 \nodepart{two} 6 \nodepart{three} 33}
;
\end{tikzpicture} $\Rightarrow$
\begin{tikzpicture}
\tikzstyle{bplus}=[
    rectangle split, 
    rectangle split horizontal,
    rectangle split parts = 3, 
    draw
]
\tikzstyle{every node}=[bplus]
\tikzstyle{level 1}=[sibling distance=20mm]
\node {5 \nodepart{two} 6 \nodepart{three} 33}
;
\end{tikzpicture}


\end{document}

Answer 1

Two examples:

\documentclass[11pt,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}
\usepackage{tikz-cd}
\tikzcdset{arrow style=tikz,
           diagrams={>=Straight Barb},
           nodes={text depth=0.25ex}
           }

\begin{document}
\begin{tikzcd}[column sep=tiny]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]   
        &               \\ 
|[draw]| -5,-1,0 
    & |[draw]| 2 
        & |[draw]| 6,7,12 
\end{tikzcd} \begin{tikzcd}\ar[r,"\text{insert 3}",Rightarrow]&~\end{tikzcd}
    \begin{tikzcd}[column sep=tiny]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]
        &               \\
|[draw]| -5,-1,0
    & |[draw]| 2,3
        & |[draw]| 6,7,12
\end{tikzcd}

\bigskip 

\begin{tikzcd}[column sep=tiny]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]
        &               \\
|[draw]| -5,-1,0
    & |[draw]| 2
        & |[draw]| 6,7,12
\end{tikzcd} $\xRightarrow{\text{insert 3}}$
    \begin{tikzcd}[column sep=tiny]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]
        &               \\
|[draw]| -5,-1,0

Is this what you like to achieve? Or should be arrow between nodes in bottom row?

\documentclass[11pt,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}
\usepackage{tikz-cd}
\tikzcdset{arrow style=tikz,
           diagrams={>=Straight Barb},
           nodes={text depth=0.25ex},
           }

\begin{document}
\begin{tikzcd}[column sep=tiny]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]
        &               \\
|[draw]| -5,-1,0
    & |[draw]| 2
        & |[draw]| 6,7,12
\end{tikzcd} \begin{tikzcd} &   \\[5ex]
                            \ar[r,"\text{insert 3}",Rightarrow]&~\end{tikzcd}
    \begin{tikzcd}[column sep=tiny]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]
        &               \\
|[draw]| -5,-1,0
    & |[draw]| 2,3
        & |[draw]| 6,7,12
\end{tikzcd}

\bigskip
\begin{tikzcd}[column sep=tiny,baseline={([yshift=1ex]current bounding box.south)}]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]
        &               \\
|[draw]| -5,-1,0
    & |[draw]| 2
        & |[draw]| 6,7,12
\end{tikzcd} $\xRightarrow{\text{insert 3}}$
    \begin{tikzcd}[column sep=tiny,baseline={([yshift=1ex]current bounding box.south)}]
    & |[draw]| 1,5 \ar[ld]\ar[d]\ar[rd]
        &               \\
|[draw]| -5,-1,0
    & |[draw]| 2,3
        & |[draw]| 6,7,12
\end{tikzcd}
\end{document}

Answer 2

You can draw the trees with forest, and set the baseline for the multipart nodes.

\documentclass[11pt,a4paper]{article}
\usepackage{mathtools}
\usepackage[edges]{forest}
\usetikzlibrary{shapes.multipart}
\tikzset{bplus/.style={
    rectangle split, 
    rectangle split horizontal,
    rectangle split parts = #1, 
    draw
},bplus/.default=3}
\forestset{mtree/.style={for tree={draw,edge={-stealth}}}}
\begin{document}
$\vcenter{\hbox{\begin{forest}
  mtree
  [{1,5}
   [{-5,-1,0}]
   [{2}]
   [{6,7,12}]
  ]
\end{forest}}}\xRightarrow{\text{insert 3}}
\vcenter{\hbox{\begin{forest}
  mtree
  [{1,5}
   [{-5,-1,0}]
   [{2,3}]
   [{6,7,12}]
  ]
\end{forest}}}$
\bigskip

$\begin{tikzpicture}[baseline={(A.base)}]
\node[bplus](A){5 \nodepart{two} 6 \nodepart{three} 33};
\end{tikzpicture}\Longrightarrow
\begin{tikzpicture}[baseline={(B.base)}]
\node[bplus](B){5 \nodepart{two} 6 \nodepart{three} 33};
\end{tikzpicture}$
\end{document}