Field ActiveColumn {get;}

if (FrameworkApplication.Panes.ActivePane is ITablePane tablePane)
{
  var mapMember = tablePane.MapMember;
  var oid = tablePane.ActiveObjectID;
  if (oid.HasValue && oid.Value != -1 && mapMember != null)
  {
    var activeField = tablePane.ActiveColumn;
    return QueuedTask.Run<object>(() =>
    {
      // TODO: Use core objects to retrieve record and get value

      return null;
    });
  }
}