The note, collected during a school sex education programme, also told of her worries about getting pregnant as a result of the attacks, which began when she was eight, it was said.
"I was forced to have sex with my father. How should I deal with it? Will I get pregnant?" the note read.
The girl, referred to as X to protect her identity, had been molested at least seven times, the High Court heard. All but the first of the alleged incidents involved rape. Not all of them made it to court.
The father, a 44-year-old builder known as H.K.H, faces two counts of rape and one of indecent assault in their Tuen Mun public housing flat between 2015 and 2017. He denied them all.
A video of a police interview with X was played in court on Thursday.