The Spirit Box can provide you with evidence to help you identify the type of ghost in your journal. You need to have the lights in the room off to use the Spirit Box in Phasmophobia, though you can leave flashlights on. Once you get a response from the Spirit Box, you might as well turn it off. You have the evidence you need from it and its continued use does nothing except produce noise and reduce sanity. It is also possible that the ghost will choose to interact with the Spirit Box again instead of for example writing in the book.
The questions that you ask the Spirit Box in Phasmophobia must be rather specific for the voice recognition to pick it up. Some questions that work well are asking the spirit where it is and its age. For example 'How old are you?', 'Where are you?', and 'Are you here?' are all questions that work well.
Also remember to check the White Board in the truck to see if the ghost will respond to everyone or only a person that is alone. If the ghost only responds to people alone then one person will have to be alone in the room, or possibly alone in the house.
Once you have started collecting evidence you can use, our Phasmophobia Ghost Identifier to help you quickly determine what kind of evidence you should be looking for and what evidence you won't find.