Make the head shape into a path. Make work path (think carefully about the tolerance, because you’ll get more points with a lower tolerance, less points with a higher tolerance, and more points means denser geometry in Cinema later on). Save the path. File>Export Paths to Illustrator.
You don’t need to go to Illustrator however. Photoshop saves it to a version of AI compatible with Cinema.
In Cinema, in the Object Manager, Merge Objects (shift-command-o). Find the path, get to extruding.