One application yo9u can use is Process Monitor
It shows more than you need and you will have to hunt through it, but it will show you paths of files in use or executed, etc.
You can also try USBDeview
,, it won't show you what is using the drive,, but it may help pull it safely.
There might be some others. And I know I saw another thread on these forums regarding the same question.
Quite honestly, I have never had a problem just yanking the drive. Ever. That I have ever noticed. This doesn't mean that others will not have problems. But, I never have. I almost always just yank the drive when I see the light ain't flashing no more. If it is and I want it to stop,, If I am really concerned about it (rarely) I will shut the system down then yank it. or try logging off.