ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Desktop.Mapping Namespace / TableView Class / ActiveObjectId Property
Example Version

ActiveObjectId Property (TableView)
Gets the ObjectID of the active row in the table. The value of the row can be null, when the table does not have object ids, the active row is the new row, or the data for the row has not been loaded.
Syntax
public Nullable<long> ActiveObjectId {get;}
Example
Get the active object ID
//Get the active table view.
var tableView = TableView.Active;
if (tableView == null)
  return;

// get the active objectID
long? OID = tableView.ActiveObjectId;
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3.1 or higher.
See Also