To create reports outside of standard reports we need to create custom report types. Custom report types can include up to 4 objects in a parent-child mode, include fields from lookups to other objects as well as a whole bunch of other features.
Custom report types needed when you have a requirement to report on more objects than standard reports allow. You can add up to 4 layers of objects as long as they have a parent-child relationship.
All objects are all related with lookups and each successive object needs to be a child or grandchild of the master object.
ContentNote, task and contact do not have the parent-child
relationship. So it is not possible.
Anyhow, you can create Activities with [OBJECT] Report Type for relating Contact and task. For more Information refer this.
But contentNote do not directly share the parent-child relationship in salesforce with Contact or activities.