OneNote Android Cache
For security and reliability reasons, private app data are stored in a directory that's only accessible by that app, unless you've previously rooted the device. The only data visible from an MTP connection are files that apps have chosen to share in this way by putting them in the "shared storage".

As well as stopping an attacker from circumventing the screen lock by doing exactly what you're doing, it also stops users breaking apps by messing about with their data files.