If you have an internal USB 3.0 port, or a header that you can change to USB 3.0 with an adapter, then yes you can plug the USB 3.0 drive in there. But I do not recommend this because even the fastest USB 3.0 flash drive like the Patriot Supersonic Magnum is slow compare to 3rd gen SSD and the SSD is cheaper in GB/$.
Okay, my guess is you want to permanently attach a flash drive inside the case just for storing Office Files? Overall, I would highly suggest against that. I do a lot with Word (300+ page files). I have four main backups (cell phone, USB drive, external HDD, and SD card) that I keep disconnected from my machine unless I'm updating the files. That way, if there is a surge, the backups will not be affected. Again, flash drives are great for backup, but not meant to be plugged in all the time.