You can find the answer to this question in Chapter 27.
#1: Bob Ewell got and lost a job with the WPA--all within a few days. Scout narrates that "he was the only man I ever heard of who was fired from the WPA for laziness. After this, citizens of Maycomb soon forgot about Bob, but he tried to stirr up trouble once more by accusing Atticus of "getting" his job.
#2: Someone tried to break into Judge Taylor's house while he was home on a Sunday night. He heard a scratching at the door, and by the time he got there, the screen door was swinging open and a shadowy figure came into his view. (We can assume this intruder was Bob Ewell.)
#3: Link Deas created a job for Helen Robinson. To get to this job, Helen had to walk a mile out of the way so she could avoid passing by the Ewell residence, because each time she passed them, they "chunked at her." So, Link Deas threatened Bob Ewell that he must never speak to Helen again--then he spat on the ground and left.