How about thanking them for the interview and asking them if it’s OK to call them next week to see how the selection process is going?
That shows gratitude AND a continued interest.
(Not that anyone posting on this thread seems to think the notes are necessary or of value...…)
How about like this:
Dear Mr. Interviewer:
Thank you so much for the chance to visit with you about the opening for the [NAME OF JOB] position we discussed today.
I really appreciate your time, as well as your input as to the factors that will affect the hiring decision.
I am very interested in being considered for the position, and hope to hear from you soon.
Sincerely,
ETC