Внутри usercontrol, определите событие, например
Event listviewItemChanged(ByVal itemIndex as integer)
Затем, в событии Listview ItemSelectionChanged внутри usercontrol, вызовите событие listviewItemChanged usercontrol:
Private Sub ListView1_ItemSelectionChanged(ByVal sender As Object, ByVal e As ListViewItemSelectionChangedEventArgs) Handles ListView1.ItemSelectionChanged
RaiseEvent listviewItemChanged(e.ItemIndex)
End Sub
И, наконец, вForm1, обработайте событие usercontrol.listviewItemchanged:
Public Sub usercontrol_listviewItemChanged(ByVal itemIndex as Integer) Handles usercontrol.listviewItemChanged
...
end sub