How to read ambient pressure on Fenix 3 HR in data field?

Can you please point out how to get ambient pressure from Fenix 3 HR? I would like to create data field (DF) derived from ambient pressure.

Evidently it is possible, because I have Fenix 3 HR and there is ambient pressure DF, also documented in manual. I have found ambientPressure and rawAmbientPressure both from api level 2.4.0, but Fenix 3 HR is 1.4.0. I must be missing something or I'm not looking hard enough.

(DF will be altitude calculated based on standard or QNH pressure. I have done this on iPhone)