public esriGeometryType ShapeType {get;}

//must support editing!
//var featSceneLayer = ... ;
if (!featSceneLayer.HasAssociatedFeatureService || 
    !featSceneLayer.IsEditable)
  return;
//Check geometry type...must be point in this example
if (featSceneLayer.ShapeType != esriGeometryType.esriGeometryPoint)
  return;

var editOp = new EditOperation()
{
  Name = "Create new 3d point feature",
  SelectNewFeatures = true
};

var attributes = new Dictionary<string, object>();
//mapPoint contains the new 3d point location
attributes.Add("SHAPE", mapPoint);
attributes.Add("TreeID", "1");
editOp.Create(featSceneLayer, attributes);
editOp.ExecuteAsync();//fyi, no await