Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
  
Dim BCol As Range, DCol As Range
Set BCol = Range("B:B")
Set DCol = Range("D:D")

'   If any errors occur make sure Enable Events is on when macro exited
On Error GoTo ExitOut

If Not Intersect(Target, BCol) Is Nothing Or Not Intersect(Target, DCol) Is Nothing Then
Application.EnableEvents = False
    If Target.Row >= 2 Then ' Minimum of row 2
        With Target.Offset(, 1) ' Put date & time in adjacent column to the right
            .Value = Now
            .NumberFormat = "dd/mm/yyyy hh:mm:ss" ' Change to suit
        End With
        GoTo ExitOut
    End If
End If
GoTo ExitOut

ExitOut:
On Error GoTo 0
Application.EnableEvents = True
Exit Sub

End Sub