What did Dill explain as the reason to why he ran away?

Dill tells a long story about being locked and chained in a basement and escaping with a traveling animal show. Then, he tells the real story of how he stole money from his mother's purse, and walked and hitched his way from the train station to the Finch house.

By an involved route. Refreshed by food, Dill recited this narrative: having been bound in chains and left to die in the basement (there were basements in Meridian) by his new father, who disliked him, and secretly kept alive on raw field peas by a passing farmer who heard his cries for help (the good man poked a bushel pod by pod through the ventilator), Dill worked himself free by pulling the chains from the wall. Still in wrist manacles, he wandered two miles out of Meridian where he discovered a small animal show and was immediately engaged to wash the camel. He traveled with the show all over Mississippi until his infallible sense of direction told him he was in Abbott County, Alabama, just across the river from Maycomb. He walked the rest of the way.

“How’d you get here?” asked Jem.

He had taken thirteen dollars from his mother’s purse, caught the nine o’clock from Meridian and got off at Maycomb Junction. He had walked ten or eleven of the fourteen miles to Maycomb, off the highway in the scrub bushes lest the authorities be seeking him, and had ridden the remainder of the way clinging to the backboard of a cotton wagon. He had been under the bed for two hours, he thought; he had heard us in the diningroom, and the clink of forks on plates nearly
drove him crazy.