Hi,
Thank you for writing to Microsoft Community Forums.
I understand that you want to add a text box to type a note on a snip using when using Snip & Sketch. However, I would like to inform that the feature to add a text box is currently not available.
I commend you for noticing this feature not being within Snip & Sketch. We would like to hear your thoughts and suggestions, as there may be other users with a similar requirement. Hence, I would suggest you to post a feedback in Microsoft Feedback Hub so that our developing team can review your suggestions and check if it can be included in the future updates.
Regards,
Nikhar Khare
Microsoft Community - Moderator