Carrick, 50, is accused of repeatedly sexually molesting a girl in the late 1980s.
The girl was allegedly assaulted on a number of occasions and Carrick would put his hand over her mouth to prevent her screaming.
On one occasion, she found herself "trapped" between a chair and a sofa and recalled trying to scream and get away, the court was told.
She did not remember him saying anything and afterwards could have "carried on as normal", jurors heard.
When she was aged 14, the girl allegedly told her mother what was going on after being found sleeping behind her bedroom door.
The defendant allegedly made admissions what he had done to the girl in a letter recovered from his medical records and signed "Dave".
In it, Carrick wrote that the girl was "not crazy" and that it was "true" but he had stopped about four months ago.
He wrote: "I know how (the girl) must feel. That's why I stopped and promised I would never go near her again and I have kept that promise and I always will."
He offered to go away and never been seen again, adding: "Sorry to you and especially sorry to (the girl) but she does not have to worry ever again. Please do not try to talk about it."
More than 20 years later, he allegedly raped and sexually assaulted a woman with whom he was in a "toxic relationship".
Opening his Old Bailey trial on Tuesday, prosecutor Tom Little KC said: "This case that you are now trying is primarily about sexual offending committed many years apart by this defendant.
"But in respect of all the offending, whenever it was committed, the defendant was, we say, very predatory and controlling.
"This was not isolated offending but part of a pattern which the defendant perpetrated over many years."
Mr Little said that, in 2022 and 2023, Carrick pleaded guilty to a "large number" of sexual and other offences relating to a significant number of other women, nearly all of whom he knew.
The first complainant in the trial was aged about 12 when she was sexually assaulted by the defendant, it was alleged.
The woman was raped "on a number of occasions" and subjected to a sex act which she did not consent to, Mr Little said.
He told jurors: "Much of this offending occurred during the course of what was a toxic relationship between the two of them and which was controlled by him."
Mr Little added: "It is also relevant for you to know that he was at the time of that relationship, as he was for many years, a Metropolitan Police officer."
Carrick has denied five counts of sexual assault relating to the girl in 1989 and 1990.
He has pleaded not guilty to two charges of rape, one of sexual assault and coercive and controlling behaviour towards the woman between 2014 and 2019.
Neither of the alleged victims in the case can be identified for legal reasons.