He also took exception to having been spied on.

他也厌恶被暗中监视。

《柯林斯英汉双解大词典》

That day he spied on her while pretending to work on the shrubs.

那天他假装修剪灌木，却秘密地监视着她。

《柯林斯英汉双解大词典》

She resented being spied on when she was sunbathing in the garden.

她因在花园里沐日光浴时被人偷看而愤恨。

youdao

For instance, they've spied on cheating husbands and wives in order to document extramarital affairs.

NPR: Gumshoes Cite More Cases, Hassles Post-Katrina

The East German secret police, the Stasi, spied on him, using his friends and contacts as informers.

ECONOMIST: Cold-war spies

He said sorry because a New Zealand law enforcement agency was judged to have illegally spied on Mr Dotcom.

BBC: Megaupload spying case brings New Zealand apology