Inside VBA editor for ThisWorkBook, you could write the following code
Dim WithEvents SheetToWatch As Worksheet
Private Sub SheetToWatch_Change(ByVal Target As Range)
If Target.Address = "$A$2" Then
If Target.Value = 7 Then
MsgBox "changed to 7"
End If
End If
End Sub
Private Sub Workbook_Open()
Set SheetToWatch = Sheets("Sheet1")
End Sub
Basically the code sets the reference of Sheet1 to the variable SheetToWatch
when the workbook opens. Declaring the variable using WithEvents
lets one capture the events.
I am using Change
event of the worksheet and checking if the cell that was changed is A2. If so, I am checking or comparing the value with 7 (it can be dynamic and depends on how you want to handle it).
See if this helps.