During an overnight visit to Campbell's house, the girl told the court how Campbell had texted her and asked if she wanted to "sneak out".
She said Campbell then collected the boy from "just down the road" so his parents could not see him, leaving along with two other boys before they travelled to a house about 30km away.
At that house, the girl said she saw some people sitting in a cabin smoking "weed" about 10.30pm.
She said the boy, who Campbell had a sexual connection with, performed a "shotgun" whereby he would blow cannabis smoke into Campbell's mouth and she would breath it in.
On another occasion, the girl said she noticed the boy's name come up in Campbell's cellphone.
A video interview Campbell had with police on June 6, 2016 was shown to Judge Harvey after the girl finished giving her evidence.
Bail was denied to Campbell and she will re-appear for sentencing on May 26.