A few months ago, I had to upgrade a system that wasn't documented. A key piece of the system was a Windows network drive that automatically connected when the workstations started up. In order to do the upgrade without accidentally breaking the system, I needed to know what user account was used to mount the drive.
A little bit of research turned up the following command, which I found really helpful. I am documenting it here just in case it helps anyone (including me) in the future.
wmic netuse where LocalName="Z:" get UserName /value
Note that "Z:" should be replaced with whatever drive letter you need to check.