Media lawyer Ambi Sitham told the Old Bailey today that Piers Morgan "said to Rebekah [Brooks] that he already knew what her splash was going to be".
"He said 'I already know what your splash is, or your cover is, because I've been listening to messages'."
Asked by prosecutor Andrew Edis QC how Brooks responded, Ms Sitham said: "She retorted, 'been hacking into my phone again, have you, Piers?'
"He said something like, 'well you've been looking at my emails' or something. It was quite a quick back and forth of bantering, I just know what I heard.
Asked how they appeared, she said: "It was pointed. There was a pointedness to it."
Rebekah Brooks denies all charges against her and the trial continues.
More top news
Five people were killed and dozens more were injured after a car and knife attack in the capital on Wednesday afternoon.
Among those expected to attend the ceremony will be former US President Bill Clinton and ex-Northern Ireland first minister Peter Robinson.
Five people have been killed and 40 injured after a car and knife attack in London on Wednesday.