The Ghost in the Castle by Chloe Friedlein

Gabby and the ghost-hunting crew are on site at a real-life castle. Reports of a mysterious "lady in white" haunting the halls are perfect for Dad's podcast. This time, Gabby is determined to debunk everything that happens. But when she hears a strange phone ringing, and the sound moves as she gets closer, Gabby learns there are some things even she can't explain.
Binding: Paperback / softback