There is no PID for the odometer in the OBD or OBD-II standard specification.
It might be there as a custom PID for your car, or done using another message format, or maybe done on a whole other bus (or not at all, but I doubt that).
I would suggest searching for a forum that specializes in your type of car.
Let us know what type of car you have; maybe someone here can point you where to go.
Once you find a group that knows your car, you can ask or search there.
Then, once you know how it is done on your car, then we can help you out programming your Carloop to do it.
Good luck searching!