@markusarvidsson - If you have access to workflows within your HubSpot subscription, you will be able to enroll contacts each time a new note is associated with the contact record and then use the 'Edit record' action to re-stamp your notes property with the current value held in it and then add on the value in the Note body of the most recently added note to the contact record:
This will give you a property with all note values within it.
Another approach to consider is creating a single object report using 'Activities' as the data source and filtering the report to show only activities where 'activity type' is 'Note', and the note properties you want to see - such as the date the note was added to the record and the note body.
Once created, you can then create a CRM card to show this report on the contact record middle pane - instructions here.
You'll then have a table collating all notes added to the record to easily access from the middle pane: