Hello Shinyu! Thank you for participating in the Apple Support Communities.
We understand that a note was recently deleted, and you'd like to recover it. We'd like to look into this with you to see how we can help.
If your notes were stored on your iPhone only, and not synced to iCloud, there may be a Recently Deleted folder on your iPhone that you can recover the note from.
If you use upgraded iCloud notes, deleted notes are moved to the Recently Deleted folder for that iCloud account, on all devices that use the same account. After that time, notes are permanently deleted from all your devices (and that may take up to 40 days).
iCloud notes that have been overwritten or have had their content deleted within the note, instead of deleting the note entirely, are permanently deleted and cannot be recovered.
The following article may also help: Delete and recover notes on iCloud.com
Make it a great day!