This is a known issue since 2005; OpenOffice Bugzilla has two bug report on this issue, one from 2005 and one from 2009. You may subscribe to the bug reports and vote them up so the issue receives higher priority.
There seems to be no solution up to now, only two workarounds:
- Pasting to OpenOffice / LibreOffice works if OneNote is closed, so copy - close OneNote - paste into OpenOffice;
- Drag&Drop should work anyway.