The screening process at the security checkpoints in the Santa clara International Airport is similar to most other airports in the world.
Security checkpoint on ARRIVAL:
After clearing Immigration you'll enter the Security Checkpoint area where you and your carry-on baggage are scanned in the x-ray machine and metal detector arch to check if you are entering in Cuba any prohibited or restricted items.
All checked baggage are also being scanned (in another area) and sniffed by trained dogs. In the ADUANA CUBA website (Cuban Customs official website), section --Passengers / At the Arrival--, you will find all information on what travelers are allowed to carry on entry, and Customs Duties
Once your carry-on baggage has been checked, proceed to the Baggage Claim area to collect you checked baggage.
Once you have claimed your baggage, a Customs Officer will collect you Custom Declaration Form. He/she will also check if your bag was marked (after X-ray scanning) for a manual search (only if they suspect something). If you have nothing to declare then proceed to the exit.
Security checkpoint on DEPARTURE:
After you've checked-in for your flight and received your boarding pass, then proceed to the Passport Control booth to clear Immigration. You’ll have to show your passport and boarding pass, and give back the other half of your Tourist Card. The Officer will stamp your passport and then unlock the door so you can move to the security checkpoint.
Your carry-on bag will be scanned (X-ray machine with conveyor belt) and you’ll have to walk through the metal detector arch, as in any other airport. In Cuban airports it's usually not required to remove your shoes, unless you've been ask to do so.
You can then exit the Screening area to get to the Departure Gate Lounge.
Check the Aduana Cuba website, section --Passengers / At the Departure-- to learn more about what you are allowed to export legally from Cuba as a visitor.