OneNote is a tool that allows users to take notes easily, without having to deal with the constraints and limitations of Microsoft Word or Excel. When you add a OneNote section to a notebook, it’s shown individually within Dynamics 365 and in order of last modified time. This integration is only possible for Dynamics 365 Online deployments. Make sure you have the System Administrator security role or equivalent permissions in Microsoft Dynamics 365.
To enable CRM integration with Microsoft OneNote, you must go to the Dynamics CRM web interface and select Settings > Document Management, as shown in below image.
Once you’ve enabled Server-based SharePoint Integration, you’ll see OneNote Integration
Note: By default, OneNote integration will be enabled for Account, Contact, Lead and Product.