How can I show ContextMenuStrip in RichTextBox when I highlight a word and right click the mouse?

The code below only show the ContextMenuStrip when I double click in the RichTextBox

Code:
   Private Sub rtb_MouseDoubleClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles rtb.MouseDoubleClick
    ContextMenuStrip1.Show(MousePosition, Right)
    End Sub
Thanks