Back Up O365 ClassNotebooks

[simpsonj]

We use Onenote / Class Notebooks extensively across the school, but a major drawback seems to be that work is not backed up anywhere when you are using the online version of Onenote, and we no longer use Onenote 2016 which took offline copies, and now use Onenote for Windows 10, which works in the cloud only. Which leads to my question, is there a way to back up all Class Notebooks, teacher work and student work, across the board? Either a paid back up or free alternative would be great.