Πιθανόν σαν audio files μόνο...
Για να γράφεις "Cubase" να φανταστώ ότι δουλεύεις σε Pc....
Δες εδώ
https://discussions.apple.com/thread/3903225
"In GarageBand with your view of all songs showing tap the Edit button, then the song you want to export, then the export arrow icon at the top left, Share Song Via > iTunes > GarageBand.
Now connect your iPad to iTunes, select the Apps tab, scroll down to the File Sharing area, locate GarageBand within that, and copy your project out to your Mac. You should be able to edit this file in GarageBand."
Tώρα για μεμονωμένα κανάλια-λογικά-κάνεις export ένα-ένα τα layers