See the article What does iCloud back up? - Apple Support
Your iPhone, iPad, and iPod touch backups only include information and settings stored on your device. They do not include information already stored in iCloud such as Contacts, Calendars, Bookmarks, Notes, Reminders, Voice Memos4, Messages in iCloud, iCloud Photos, and shared photos.
See your recordings on all your Apple devices - Apple Support
Share a recording on Mac - Apple Support
Restore Apple Watch from a backup - Apple Support
Your Apple Watch is backed up automatically to your paired iPhone, and you can restore it from a stored backup. Apple Watch backups are included when you back up your iPhone—either to iCloud, or to your Mac or PC. If your backups are stored in iCloud, you can’t view the information in them
So voice memos will not be found or backed up .