I may be wrong, but that isn't possible through CSV.

click on Organisation>Import/Synchronize

You only have the following options for CSV:

Import users from CSV
Import parents from CSV
Relink teachers to manageable groups from CSV

Import placeholders from CSV

Import photos from ZIP

If you need to import notes for devices, you will need to do this via the API

Hello Rob,

we are working with importing placeholders from CSV. But why is it possible to export notes as CSV to Inventory but not to import?

Peter