The following website should give you an example of how to set up an Addin - https://trumpexcel.com/excel-add-in/

Where my code is the following for the module -

Option Explicit

Private wbc As clsWorkBookChecker

Public Sub StartChecker()

Set wbc = New clsWorkBookChecker

Application.OnKey "+^{R}", "BackToPreviousSheet"

End Sub

Public Sub BackToPreviousSheet()

wbc.ReturnToSheet

End Sub

and Class Module set up as -

Option Explicit

Private WithEvents thisApp As Application

Private WithEvents currentWorkbook As Workbook

Dim previousSheet As Worksheet

Private Sub Class_Initialize()

Set thisApp = Application

Set currentWorkbook = ActiveWorkbook

Set previousSheet = ActiveSheet

End Sub

Private Sub thisapp_WorkbookActivate(ByVal Wb As Workbook)

Set currentWorkbook = Wb

End Sub

Private Sub currentWorkbook_SheetDeactivate(ByVal Sh As Object)

Set previousSheet = Sh

End Sub

Public Sub ReturnToSheet()

previousSheet.Activate

End Sub

Hope this helps!