as bad and cruel as this sounds,unless you are planning on butchering this pig or raising it until it dies of old age,in a pen that is built like ft.knocks so it cant escape, the best thing for it is to let it try to survive on its on and if it doesnt make it so be it.wild pigs/hogs are a nuisiance(sp) and when they get over populated they will destroy everything from grass to trees in in search of food including,but not limited to your yard,garden and flower beds.Heaven forbid they find your grains/feed you put out for your barnyard animals,they will be regular visitors at your place.
now with that being said,the best way to trap a hog is to soak corn in a 5 gallon bucket full of water and yeast until it sours helps piggy find it better, then pour the water out and soak it in diesel fuel for a day to keep the coons and squirrells out of it. while that is soaking, build a pen with a guillotine(sp) door with a rope with a stick tied to the end, over the limb of a tree and fix the stick loosley under a root in the ground so it slides easily out from under the root then pour the corn over the root when piggy starts rooting in the corn he knocks the stick out causing the door to comes down and piggy should be trapped
P.S.
use heavy gauge fencing and wood or steel materials.I know you said a little pig but big hogs can/will find it too