public Geometry Sketch {get;}

// SketchCompleted event is fired by 
//  - COTS construction tools (except annotation, dimension geometry types), 
//  - Edit Vertices, Reshape, Align Features
//  - 3rd party tools with FireSketchEvents = true


//Subscribe to the sketch completed event
//ArcGIS.Desktop.Mapping.Events.SketchCompletedEvent.Subscribe(OnSketchCompleted);

private void OnSketchCompleted(SketchCompletedEventArgs args)
{
  // get the sketch
  var finalSketch = args.Sketch;

  // do something with the sketch - audit trail perhaps
}