How do I see what applications or services are preventing an external flash drive from ejecting?

I know there are general solutions out there to deal with problems ejecting hard drives, but I'd like to get more specific and understand what applications are causing problems so that I can deal with them without closing *every* app or by logging out when I'm in the middle of working. Or worse still to be unable to reformat an external disk or to do disk operations like create a bootable installer which is what prompted me to ask this question. Looking in the Activity Monitor > Disk Tab didn't seem to be very helpful. I'd have to go by a hunch and check the info for an app, look at Open Files and Ports tab, scan the Open Files for directories that match the problematic disk and or volume. This process is needlessly tedious. There's got to be a better way. I'd like to be able to use an Application or a Terminal command, point to the disk or volume in question and have it return what Applications are preventing the disk from ejecting. Are there software or utilities that specialize in preventing applications from needlessly molesting external drives? I would consider a well written script/service. I don't mind using command line utilities to get the job done. I was considering downloading Little Flocker again and seeing if I could apply it to my external drives. Every application would be blocked from accessing my external drives until I aprove it or make a rule via Little Flocker. But apparently Little Flocker was bought out by F-Secure :(. For what it's worth I'm on MacOS Sierra V. 10.12.5