"It is very disturbing," Ms Grahame said. "It is a worry that people are using these things to look at houses, possibly to see if people's houses are worth breaking into.
"People need to be aware that they think they have got privacy in their own home and they haven't. I don't see why the average individual needs a drone."
Mr Kriticos said he had returned to the apartment when he heard buzzing on the balcony and spotted the silver and white drone.
"It was deliberate," he said. "It wasn't accidental it hovered there. Heaven knows how long it had been there before I noticed it.
"It was definitely watching. I stood there and watched it for three or four seconds, then I stuck my finger up at it and it flew off.
"It was close enough that if I was holding a broom I could have whacked it."
Drones are not permitted to fly within 30m of residential buildings, boats, cars or people. Fines of up to $9000 apply.
Civil Aviation Safety Authority spokesman Peter Gibson said they would investigate, but it was difficult when not knowing who owned and operated the drone. He said there was a slew of other laws that could have been broken.
Police were called, but the couple said there was very little police could do.
"Unfortunately, these things have a 6km radius," Ms Grahame said. "In built-up areas like this you could fly it from anywhere, whether it is in our building or somewhere nearby, and it would be difficult to catch."
Mr Kriticos said they had been rocked by the invasion.
"We used to leave home and keep the balcony doors ajar so the dog could go to the patio any time it felt like," he said.
"But after this we have been shutting it and dead-bolt locking it. It has certainly made us change a few of our habits."
He pointed out they had a doggie door.
"Now we feel like we have to sit in our home with our blinds shut," he said.
"It is wrong - you shouldn't have to do things like that in your own home.
