I don't believe there's an API for that. The reason is there is not a 1:1 relationship with the Job and the Task or Process.
A Job might include multiple processes or tasks. Now I believe you want to know on which current process or task the job is waiting for.
Again, there is no API, but you should be able to figure it out by querying the database. Howerver this is not supported and is at your own risk.