If you have brainstormed tasks in OneNote, you can easily convert them to tasks in Outlook by applying an Outlook Task flag. You can find it on the Home tab, in the Tags group. Or, you can use the Ctrl+Shift+1 to 4 to set a flag for today, tomorrow, this week or next week. Ctrl+Shift+F will allow you to set a custom flag. Now, you should find all these tasks you just created in Outlook. Whether you mark them complete in Outlook or in OneNote, the status will synch up.
If you notice a lag, press F9 in Outlook or choose Synch under settings (File tab) OneNote.