Fiona Radford, from Langwith, snipped a cable linking underground probes to a seismic monitor with secateurs, while walking her dog in a field, off Devonshire Drive, on January 20.
Prosecutor Simon Rowe said INEOS, which owns the device, put CCTV footage of the incident on social media and tracked down Miss Radford because she was wearing a distinctive hoodie.
In police interview, she said: “I did it. I cut it. I was angry. I wanted to hurt them like they have hurt us.”
“She had been visited by an elderly lady the day before who was upset because the fields had been damaged by vehicles going on and off the field,” Mr Rowe said.
She contacted INEOS, Derbyshire County Council and landowners, the Welbeck Estates, to complain, but received no response, he said.
“She said she did it out of rebellion for what INEOS had done,” Mr Rowe said. “She wasn’t hiding her actions, she did it in daylight.
“Later she said she regretted it, and wouldn’t do it again, and would stick to protesting.”
INEOS intend to pursue her for the £570 cost of repairs through civil means, the court heard.
Michael Little, mitigating, said: “Prior to this her protests had been limited to putting posters in her window.”
He said Miss Radford had seen red when her elderly friend told her she couldn’t use her disability scooter because of the “unfortunate mess” the countryside had been left in by INEOS.
Police initially contacted her daughter because the hoodie seen in CCTV belonged to her, but she was at university, and when Miss Radford found out, she contacted police.
The bench was shown pictures of the area which showed it was “a mess, without a shadow of a doubt,” Mr Little said.
FIona Radford, 49, of Devonshire Drive, Langwith, admitted criminal damage when she appeared at Mansfield Magistrates Court, on Friday.
She was given a six month conditional discharge and ordered to pay £85 costs and a £20 government surcharge.