If you wrote this ActiveX control, then you should've created a MouseMove event as well., because most of all ActiveX controls have MouseMove event. So anyway, if you do have ti, then you already have coordinates passed as arguments. Here's an example:
Code:
Private Sub MyControl_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
MsgBox "X: " & X & vbCrlf & "Y: " & Y
End Sub