It's a rare look at the machine some say is at the core of Scientology. It's called an E-meter, short for electropsychometer.

Karen de la Carriere is lifting the veil of secrecy over one of the controversial church's great secrets. She used to be such a high level in the Church of Scientology, she could be compared to a cardinal in the Catholic church. Her ex-husband once served as president of the church.

Scientology's website calls the E-meter a "religious artifact" and warns "it is for use only by a Scientology minister or a Scientology minister-in-training."

De la Carriere told INSIDE EDITION, "This is mandatory to be done several times a day. There is no power of choice there."

De la Carriere says Tom Cruise would be required to use a machine just like it several times a day, to telepathically contact spirits.  

"He would be holding the cans, doing the breath tests. And say, 'This is the session,' " said de la Carriere.

She says Scientologists believe that when the needle moves all the way to the right, it signals communication with a spirit.

"Telepathically, you would get the answer, 'I am a lion. I am three lions in the arena. I am a gladiator,' " said de la Carriere.

On the internet, INSIDE EDITION found a photo of another famous Scientologist, a young John Travolta, using the device.

And get this—we actually found E-meters for sale on eBay costing anywhere from $20 to $25,000!

Tom Cruise has always had a deep interest in religion and spirituality. A rare photo shows him in seminary school when he was 14 studying to become a Catholic priest. And his daily routine back then couldn't have been more different than his life now as a movie star.

Michael Daly of theDailyBeast told INSIDE EDITION, "He got up at dawn. Said his morning prayers, went to mass, and studied very hard."