“While the U.S. government has claimed for years that Chinese companies are building surveillance technology into devices exported to the U.S. (such as networking equipment), it was revealed in 2014 in the book “Global Surveillance” by Glenn Greenwald that the NSA’s “TAO” (Tailored Access Operations) unit has been intercepting and tampering with technical devices in transit since at least 2010.”
Pack your laptop in a box of colored lentils, photograph the pattern, and compare it when you get back. Nobody can open the box and put every lentil back in the same spot. Glitter nail polish on the screws works on the same principle. The threat model is not paranoia. The NSA was caught doing exactly this to shipped hardware.