Stinkbugs are brown-gray shield-shaped insects about 0.2-0.8 inches in length, and, of course, they release a nasty odor when provoked.
Try a soapy water trap: mix soap and water in a shallow pan, placing a light source nearby. The stinkbug will follow the light source, drowning in the trap. You can also suck 'em up with a vacuum cleaner.