subprocess is a module of Python that can be used to implement multiprocessing
To learn more about subprocess, consult its documentation which starts:
The subprocess module allows you to spawn new processes, connect to their input/output/error pipes, and obtain their return codes.
For an example of using subprocess with ArcPy, you could consult an Esri blog entitled Multiprocess Geocoding which says:
Before exploring multiprocessing and GPU programming, don’t forget Python’s subprocess module. This supports multiple independent processes but does not require thread safety – just a simple approach of a master script and a worker script.
