You can’t. Any equipment that’s not currently enabled in the watch is clearly available for use in future software updates but there’s nothing the user can do directly that will turn these things on or off.
Mike | London, UK
Blaze, Surge, Charge 2, Charge, Flex 2 - iPad Air 2, Nokia Lumia 925 (Deceased), iPhone 6
Take a look at the Fitbit help site for further assistance and information.