Option Explicit
Dim celluleAvant
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim celv As Range
Set celv = Range("A2:Z100")
Dim celd As Range
Set celd = Range("A1")
If Not IsEmpty(celluleAvant) Then
If Not Intersect(Range(celluleAvant), celv) Is Nothing Then
Calculate
celd.Value = Now
End If
End If
celluleAvant = Target.Address
End Sub