If they were jobs inside a workflow, you can declare a workspace to save/restore a folder.
However, it sounds like your jobs are to run independently. There isn’t anything native in CircleCI for that, but I’d suggest creating a tarball of the cache and rsyncing it to an external server. It obviously has the delay of the network, but this can still be much faster than the build process that created the cache in the first place.
Do you know roughly how big the cache folder would get?