Assuming you have a blank sheet name "Sheet2"
Hit Alt+F11 to bring up the VBA editor
On the left should be a window.
Look for the name of the sheet that has the dynamically updated cell.
click on it.
Choose Worksheet on the first drop down menu.
Choose Change on the drop down menu and paste the following code.
Code:
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = Range("A1").Address Then
Worksheets("Sheet2").Cells(65536, 1).End(xlUp).Offset(1, 0).Value = Target.Value
End If
End Sub