I believe the Change (worksheet event) is what you're looking for.
Check it out in VBA Help.

In Sheet1 (or whatever sheet):



Private Sub Worksheet_Change(ByVal Target As Range)

If Target.Column = 1 Then

Target.Worksheet.Cells(Target.Row, 2) = Date ' or Time or Now (for
both)

End If

End Sub

A procedure could not be triggered by
a change in the value of cell. However whatu can try is making the workbook
share and one can see the track changes so see when was any entry updated on a
cell

: A procedure could not be triggered by a change in the value of cell.

Isn't that what the change event is for?

Private Sub Worksheet_Change(ByVal Target As Range)

' Do something

End Sub

Try this in the worksheet code

Private Sub Worksheet_Change(ByVal Target As Range)
If Intersect(Target, ActiveSheet.Range("A:A")) Is Nothing Then Exit Sub
Range("B" & Target.Row).Value = Now()
End Sub