Get player's vertical height /altitude?

[alleycat 28]

I am trying to read out the players vertical height and present it in a hint.

hintsilent format[" Your current height: %1",(getPosASL _caller)];

This however displays all 3 coordinates of the player's position. How to "extract" the third variable and only use that?

[CarlGustaffa 4]

hintsilent format[" Your current height: %1",(getPosASL _caller) select 2];