How have drone sensors advanced?

Large Predator B drones, built by General Atomics Aeronautical Systems and first flown in 2001, are used by the military to perform multi-mission Intelligence, Surveillance and Reconnaissance (ISR) missions over land or sea. Sensing payloads in the MQ-9A Predator B remotely piloted aircraft (RPA), include:

Multi-Spectral Targeting System Model B (MTS-B) Electro-optical/Infrared (EO/IR),
Lynx multi-mode radar
Multi-mode maritime radar
Automated Identification System (AIS)
Signals intelligence (SIGINT)/ Electronic Support Measures (ESM) system
Communications relay

Since 2006, the U.S. Customs and Border Protection agency has been flying drones over the Arizona desert and southwest border with Mexico.

Thirteen years ago, Miami police were among the first to evaluate Honeywell International’s Micro Air Vehicle or “Honeywell MAV” to fight crime. Weighting 16 pounds when empty and 18 1/2 pounds when fully loaded with fuel, the MAV was 14 inches in diameter and 22 inches from its feet to the top, the small pilotless drone featured electro-optic or infrared sensors.

Today, sensors in drone applications can be classified as optical, acoustic, position, touch, environment and other sensors. Sensor types include:

inertial sensors (accelerometers, gyroscope, magnetometers, tilt)
image sensors (infrared, thermal, multispectral, 3D)
speed and distance sensors (radar, LiDAR, proximity),
position sensors (GNSS/GPS),
pressure sensors (barometric, differential),
current sensors, ultrasonic sensors, light sensors, altimeter sensors, flow sensors
chemical, biological, radiological and nuclear defense (CBRN) and other sensors

In consumer type (hobbyist and professional) drones such as the DJI Mavic Mini, the primary payload is a camera sensor. The Mavic Mini has a 1/2.3” CMOS image sensor with effective pixel rating of 12 MP. It has takeoff weight of 249g and unfolded dimensions (with propellers) of 245×289×55 mm (L×W×H). For navigating, Global Navigation Satellite System (GNSS) capabilities include: GPS and GLONASS.