This example adds to myDocument
an oval and a callout that points to the oval. The callout text won't have a border, but it will have a vertical accent bar that separates the text from the callout line.
Set myDocument = ActiveDocument
With myDocument.Shapes
.AddShape msoShapeOval, 180, 200, 280, 130
With .AddCallout(msoCalloutTwo, 420, 170, 170, 40)
.TextFrame.TextRange.Text = "My oval"
With .Callout
.Accent = True
.Border = False
End With
End With
End With