How to Enable Apple Pay on Your Apple Watch
Apple Pay on Apple Watch is secure. Remember, Apple Pay differs from most other mobile payment solutions because your credit or debit card number is never visible to the retailer — and thus safer to use.
When you add your card information to Apple Watch, that unique and encrypted Device Account Number (DAN) is assigned and stored on a dedicated chip inside the watch (that Secure Element technology, like with the newer iPhones and iPads).
“But wait a sec,” you’re thinking. “Apple Pay on iPhone requires your fingerprint on the Touch ID sensor, so how do I do that on Apple Watch?”
To enable Apple Pay on the watch, you need to create a four-digit passcode using the companion Apple Watch app on your iPhone. This passcode is used to authorize Apple Pay whenever you put the watch on your wrist. Go to My Watch→Settings→Passcode to enable and create a passcode using the virtual keyboard.
And as you might guess, those sensors on the back of the watch aren’t just used for your heartbeat; they know whenever the watch has been taken off. And you must once again type in your secret passcode when you put the Apple Watch back on your wrist.
That way, if someone puts on your Apple Watch or tries to use it without slapping it on his or her wrist, your information is safe because the other person won’t know your passcode.