Midget is an offensive term for someone who is much smaller than average. While it's acceptable today to describe an inanimate object with the adjective midget, it's never okay to use the word for a person.
Long ago, people felt free to describe little people as midgets — for example, the actors who played the Munchkins in the 1939 movie "The Wizard of Oz" were routinely described as midgets. Today we'd avoid describing these actors by their physical characteristics, but if we did they'd be called "little people," "dwarfs," "LP," or even "people of short stature." Save midget for midget crabapples or midget submarines.