Good thinking. Since you are taking a conservative approach (which is good) then consider adding at least one more backup drive to Time Machine. This is in an abundance of caution against something going wrong. If you think that's unlikely, consider the fact something has already gone wrong, otherwise you wouldn't need to restore a backup. One and only one backup drive does not comprise a robust backup strategy anyway. TM will back up to as many as you wish to provide, in "rotation" fashion.
Assuming you do not use iCloud for Notes, read on.
Click the desktop background or select the Finder icon from the Dock. Picture below:

Select it. That makes sure the Finder is frontmost. Confirm it by moving your Mac's cursor all the way to the upper left of the screen. You should see this:

Then, click the Go menu > Go to Folder...
A dialog will open. In its Go to the folder: field, type (or better yet, copy / paste) the following:
~/Library/Group Containers/
Make it look exactly like this:

... and click the Go button.
A Finder window will open. Scroll down and select (click once) the folder named
group.com.apple.notes
Don't open it. Just leave that folder selected. That is the folder you need to restore — the entire folder.
Then, click the Time Machine icon in your Mac's menu bar, and "Enter Time Machine..."
Allow a few minutes for the Time Machine interface to load. That can take ten, twenty minutes or more if your TM history goes back many months or years.
When it calms down navigate "back in time" and locate the group.com.apple.notes folder you want to restore, then click Restore.
A dialog will appear:

- "Keep Original" amounts to "Cancel", while "Keep Both" amounts to "let me decide later".
Assuming you are comfortable with restoring that Notes folder click Replace.
Done.
For reference: Restore items backed up with Time Machine on Mac