Catholics believe that death is not the end of the human soul. The dead face a particular judgment which leads to damnation or salvation; those led to salvation may enter eternal life immediately or after a period of purification in purgatory. We don’t actually know what purgatory entails, although we do believe that we can have contact with the dead who have gone before us. That’s what we do when we pray for the intercession of the saints. But the Church does not teach that tormented souls linger on earth like the ghosts of popular imagination.
The Catholic Church does teach that a person or place can be possessed by the Evil One, although this is extremely, extremely rare. In such cases a Rite of Exorcism can be performed, by a specially trained and designated priest, asking “publicly and authoritatively in the name of Jesus Christ that a person or object be protected against the power of the Evil One and withdrawn from his dominion” (Catechism of the Catholic Church, 1673).
If you think your house is haunted, ask your parish priest for help. Tell him what makes you think there might be something more than creaky floorboards at work, and he will know what to do next. A house blessing or prayer service, which reminds you of God’s presence and calls out the goodness that is already there in your home, might help to restore your peace of mind.