Hi - yes, this is possible but only in conjunction with the Garmin Connect app. Download from the Apple Store.
How to pair the HRM-Pro/Pro Plus with the Garmin Connect App:

Create HRM-Pro/Pro Plus and then simply follow the steps below - you should then have established a connection:
Open the menu. ...
Tap Garmin Devices.
Tap Add Device.
Tap Connect when the HRM-Pro/Pro Plus is found.
Tap Pair for all Bluetooth pairing requests.

I haven't tried it, but I don't think it works.