I wouldn't put it past Adrian Newey to have come up with some incredibly clever and intricate system which is either undectable (while effectively cheating) or is just a very clever system using progressive springs, pivot locations and linkages so that the actual geometry is effected by the car mass. The other way would be to do something along the lines of the McLaren duct whereby the driver can have some influence over the rideheight without there being a mechanical or electronic system in place.
I'm surprised no one's actually measured the car rideheights (even roughly) via TV footage of the cars in quali and then at the start and ewnd of the race... can't be that difficult can it? They did it in the Italian Job remake after all .