After you install watchOS 4.2, you will see on your paired iPhone with iOS 11.2 installed, an Apple Pay Cash option within the Watch app’s Wallet settings. Just turn the option to “ON” and sign in with your Apple ID.
Next, you will see an Apple Pay Cash prompt appear with “Continue.” Press that and your iOS device will start setting Apple Pay Cash up to work. After the process is completed, you will see your Apple Pay Cash card appear next to any other cards you have that are connected to your Watch.
Tap on the card and you will find more information and settings. You can also verify your identity to ensure that you can send cash through the service. After verification, your new Apple Pay Cash card will appear in your Apple Watch Wallet. You can easily swipe up anytime to see your card balance and double click to pay at any store with Apple Pay.
In your Messages app on your Apple Watch, you will also see a new Apple Pay button that will let you adjust the payment amount. When you tap on the “Pay” button, you will get a prompt to double click on the side button to send the payment. Processing will take a few moments only.
You can click on the Apple Pay Cash image to confirm that a payment is completed. For the recipient, there is a message confirming that payment was sent. Clicking on the icon in Messages will help the recipient see more information about the payment.
If the payment says “Pending,” it is possible that the other user has notset up Apple Pay Cash on their device. You can cancel the payment if needed by tapping on the Apple Pay Cash image in the Messages thread, hitting view payment information and then canceling the payment.
Anyone you are connected to via Messages like your friends, family or colleagues can request payment from Messages. You can send the payment via your Apple Watch. Adjust amounts too if needed and then double click to pay.
You can always check the balance on your Apple Pay Cash Card using the Wallet app.