That'd be fun, but I am pretty sure they get it electronically into their bank account — as in, no money is ever made for their salaries, just like most white collar workers.
As a side note: In some countries, central bank employees are the only individuals that can actually hold non-paper M0 (or MB?) money, since they get paid their salaries into a central bank account, which are otherwise only available to commercial banks. This used to be the case in Germany and Austria, but has been phased out at some point, as far as I remember.
But even if Fed employees just get paid in regular old M1 demand deposits, that's money nonetheless.
The Bank of England used to offer personal bank accounts to their employees, but they phased it out after 2015. Not sure if these accounts were exactly the same as those used for central banking though.
