It shows hypocrisy through some of its characters.
1. Bob Ewell. This man is the lowest scum of the earth, who beats his children, is a drunkard, is racist and ignorant, and yet he claims to be better than a decent, hard-working, family-oriented man with total integrity and morals. He gets up on the witness stand like "a little bantam cock" (proud, strutting rooster) and proceeds to claim the moral high-ground on Tom Robinson, all the while lying through his teeth and doing a poor job of covering up his more base qualities. Bob Ewell is a hypocrite at best, and an immoral, evil man at worst.
2. Miss Merriweather is a hypocrite; at the missionary meeting she gets all weepy-eyed and soft-hearted at the thought of the poor Mrunas in their deplorable situation, yet does nothing more than that-put on a show of sympathy. And nearly in the same breath she turns around to bad-mouth the black people in her own neighborhood, people who also have a deplorable situation that she could actually do something about, but instead, she declares to the black people, "you live your way and we'll live ours." She is a hypocrite because she touts righteousness and charity, but does not act on it when situations right in front of her arise.
3. Walter Cunningham and the mob gang. While Walter Cunningham isn't one of the worst characters in the book, he does display hypocrisy as he goes about his everyday business living a moral, upright life, but when it comes down to granting a black man kindness and equal treatment, he goes for the pitchfork. Scout recognizes him in the mob that come for Tom at the jail, and talks to him, which brings a bit of his hypocrisy to the spotlight, and it actually shames him into leaving. So that is a good sign for him; he recognized how ridiculous and hypocritical it must have seemed for him to be riling up a crowd to cause harm to a good man, but to go about his normal life with decency and morals that he was trying to instill in his children.