The only time I have seen inspections to determine if chains are in your possession are big rig truckers. In this case, Caltrans is doing the inspections, not CHP.
From a practical standpoint, CHP does not have the staffing to stop every vehicle on a major highway to see if chains are buried in the trunk somewhere.
From a common sense standpoint, such a check point would create a traffic jamb 50 miles long.
This does mean inspections might (but very unlikely) occur on sparsely traveled secondary roads in the Sierra.
CHP and Caltrans will turn you around at a chain control checkpoint if chains are not mounted on a vehicle that should have them on.
