Here is a way
Code:
'===========================================================
'- CHECK FOR CHANGE IN A VLOOKUP VALUE
'- WE CANNOT CHECK FOR THE CHANGE DIRECTLY (eg.TargetValue)
'- BECAUSE IT DOES NOT FIRE A CHANGE EVENT ITSELF
'===========================================================
'- code runs whenever a change is made in the ws
'- Goes into ws code module. Right click tab. view code
'- Brian Baulsom November 2008
'============================================================
Private Sub Worksheet_Change(ByVal Target As Range)
'- Saves the value in this subroutine
Static A3value As Variant
'--------------------------------------------------------
'- check if the saved value is the same as it was
If A3value < Range("A3").Value Then
A3value = Range("A3").Value
MsgBox ("A3 has changed to " & A3value)
End If
End Sub