How to determine which processes are running on outdated packages and needs restarting?

So, I know that it is possible to view or recover deleted files that are currently being used by a process. I've found out that this also applies to packages that were updated. So, let's say we update a package, but that package is still being used by another process and ultimately running on an older version of that package since it has not been restarted. So, my question is, how do we determine the processes that are running on an older version of that package due to it not being restarted?