Sub Demo()
Application.ScreenUpdating = False
Dim CCtrl As ContentControl, Rng As Range
For Each CCtrl In ActiveDocument.ContentControls
  With CCtrl
    If .Range.Information(wdWithInTable) = True Then
      Set Rng = .Range.Cells(1).Range
      With Rng
        .End = .End - 1
        .Bookmarks.Add CCtrl.Title, Rng
      End With
    End If
  End With
Next
Application.ScreenUpdating = True
End Sub