Measuring is as simple as having the tools, the specs, and the technique.
You will need a magnetic or clampable dial indicator with a long probe. This should be positioned and tentioned over the valve to read verticle movement. All of the valve lash should be adjusted out, till the valve is depressed.
With your dial indicator zero'ed rotate the engine by the crank bolt in the direction of rotation till there is 2.0mm of valve movement (intake valve). Look at the crankshaft balancer and read the degrees off the wheel next to the pointer.
The deg should be 9 ATDC with new chain and 11 for chains of 20000km. This spec is for the cam with #11 stamped in the rear journal.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician