Eimear Cook, the ex-wife of golfer Colin Montgomerie, has told the court about a meeting she says she had with former News of the World editor Rebekah Brooks in 2004.
In Cook's recollection of the conversation, Brooks appears to refer to the practice of hacking voicemail messages.
Brooks and the other defendants deny all of the charges against them.
Cook told the court:
She said it was so easy to do and she couldn't believe that famous people who have all these advisors and they don't know they need to personalise or change their pin code to make them more secure.
The court heard that the meeting took place in September or October 2004 at the home of a mutual friend. The trial continues.
More top news
Takeaway food and alcohol are causing a growing obesity crisis among pets, according to a leading animal welfare charity.
Teacher shortages in England continue to grow and the government has missed recruitment targets, the National Audit Office says.
The way the government plans to pay for social housing tenants to buy their homes is "extremely questionable", MPs warn.