Are you just trying to figure out which control the user Right Clicked on to make the ContextMenuStrip to appear?
Private Sub ContextMenuStrip1_Opening(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles ContextMenuStrip1.Opening
Dim ctl As Control = ContextMenuStrip1.SourceControl
Debug.Print("Source: " & ctl.Name)
End Sub