Professional nanny Ashley Stanley was changing 1-year-old Samantha's nappy when the baby monitor - which has a built in security camera - caught her attention.
Speaking with Click2Houston.com, she explained: "I kept hearing this strange noise from over there by the crib."
After listening intently, Ashley soon realised that the noise she was hearing was, in fact, a man's voice.
And that the stranger was speaking through the baby monitor.
Before too long, the voice began speaking directly to Ashley, making it clear that someone was watching her and the baby.
She said: "They kept telling me that it's a cute baby and 'wow that is a poopy diaper.'
"I was like, 'My goodness, are they watching me like right now?'"
The baby monitor was fitted to ensure that Samantha's parents could check in on her from work using their mobile phones.
However someone unlawfully hacked the system and accessed the camera, which can be controlled remotely to survey the entire room - and even down the hallway into other parts of the house.
It remains unclear whether the hacker will be found, but Ashley - and Samantha's parents - have vowed not to give him a second chance.
"We unplugged it and I'm afraid to plug it back in," said Ashley.