Track Activity using Notes

Hi

I need to be able to track and filter leads by the date the most recent NOTE was made.
I see that you can filter by tasks, calls and events (activities), but there isn't a note option.

What would be simpler and ideal is if the "modified time" of a lead was updated every time some activity (i.e. a note) was recorded. Is it possible to do this? At the moment, a field needs to be changed in order for the activity to be registered.

If not, please would you let me know how to filter the lead records by the most recent note created time.

Thank you.
Eleanor