You can try to use selectionChange event.
You can evaluate which cell has current focus and keep track of last cell range that had focus prior to the current cell range.
Private Sub Worksheet_SelectionChange(ByVal currentRange As Range)
Static lastRange As Range
If Not lastRange Is Nothing Then
If lastRange.Address = "$A$1" Then
End If
End If
Set lastRange = currentRange
End Sub
Regards