[Blind-sysadmins] OneNote: How to convert notebooks into something more readable like HTML?

Hi all, Our people over here have converted all documentation into OneNote. The .one and .onetoc2 files are residing on a network share. the main notebook also contains a bunch of sub notebooks as well. The .one files are the notes which also seem to contain more than one note per file. Anyone knows how to convert the whole stuff into HTML or something more readable than the OneNote format? We have OneNote 2010 and OneNote 2016. Both versions seem not all that accessible. Greetings and thanks, Simon