Assuming you have Time Machine backups, and assuming the text you recently deleted was in an earlier version of your notes that was backed up by TM, you should be able to recover your Notes data from an earlier backup.
However, you will want to make sure you have a current backup as well - otherwise any new notes you've added may be lost.
So, the way I would approach this is:
- Disconnect your Mac from the internet
- Make sure you have a current backup
Restore the entire Notes folder from an appropriate earlier backup - it's located at:
Access the data you need
- Copy the content you accidentally deleted and paste it into another file (e.g. a TextEdit doc, etc)
- Restore your notes from the backup at Step 2 above
- Edit the note to include the missing data you copied at Step 5
- Once you're happy with everything, reconnect your Mac to the internet
NOTE: Steps 1 is necessary to ensure that iCloud doesn't sync old data across your devices.