Adding a customer note to a customer’s profile can help you and your sales team keep track of a customer’s order/quote preferences, your previous and upcoming meetings with them, follow-ups, or any other information that you think is important.
Customer notes only appear on the customer’s profile and not on orders or quotes. Customers are therefore not able to see these notes.
Related articles:
How do I manage customer notes in the web console?
How do I allow my sales reps to edit customer notes?