Compare and contrast the Robinson Place with the Radley Place in To Kill a Mockingbird. Do ghosts exist at both places?
To answer your question first, one could certainly argue that "ghosts" exist at both places. At the Robinson place, Helen Robinson surely feels the presence of her husband Tom after he is killed. Similarly, a sense of injustice must haunt their homestead with Tom's "murderer" still roaming free. As far as the Radley place, Boo certainly is not a ghost or monster, but the loss of his childhood and a decent life cast a shadow over the Radley place.
The two places do share some similarities. Both house victims of injustice. Boo's father's punishment of him is too extreme for what Boo and his friends did as teenagers. Likewise, the Robinson family loses their father and provider because of someone else's false accusations. There is a sense of mourning in both houses.
The difference between the two houses is that Boo is free to escape his "prison" if he could bring himself to do so. Helen Robinson, after her husband's death, still has to walk around carefully, never knowing when Bob Ewell might stalk her or someone else might threaten her. She still lives in a prison of sorts.