CRM Online can be integrated with OneNote Online by linking to the OneNote record and Excel Online spreadsheets can be live updated to CRM Online. It is important that companies set a policy as to what kind of data should be stored in OneNote vs CRM Online. Keep in mind there is no way to control user data within OneNote.
Both the One Note integration and the Excel Online integration are not available for CRM premise deployments.
For more information on CRM Online integration, contact us.