Joshua Scarth, 25, was jailed for eight months after a court heard police set up a spy cameras over concerns about money going missing.
Leeds Crown Court heard Scarth was filmed putting on latex gloves before getting on his hands and knees then searching in a storeroom where money was kept.
The footage showed him leaving the room with cash.
He was also filmed urinating into the sink and into cups before giving them to the couple to drink out of.
David Ward, prosecuting, said Scarth worked for a company called Flexicare at the time of the offending in March this year
The couple, who live in Netherton, Wakefield, both suffer from health problems and received visits from carers three times per day.
Mr Ward said cameras were installed after money totalling £900 went missing on different occasions.
Nothing untoward happened when other carers visited the property apart from.
Scarth was the only person filmed going into the storeroom and was also seen to come out of the room holding cash in his hand.
He took a further £120 before being arrested. He continued to deny doing anything wrong even after being confronted with the video evidence.
Scarth, of Grove Road, Wakefield, pleaded guilty to theft.
Mr Ward said the couple and their relatives had been devastated by the offending and now found it difficult to trust carers who came into their home.
Tony Sugare, mitigating, said Scarth had been sacked from his job.
He said: “I accept that this is a despicable case and a very serious one.
“It may be small consolation to family members present who are here but the defendant does wish to apologise for his behaviour and he does have remorse for what he has done.”
Mr Sugare said a report into his client’s offending could not find a reason for the way he behaved.
He added: “He does not smoke, he does not drink, he does not gamble and there is no reason for why he did it.”
Jailing Scarth, Recorder Peter Pimm said: “You do not need me to tell you, because you recognise it, that this was a despicable crime.
“It is hard to imagine more vulnerable victims than your victims in this case.”
After the case, a relative said the victims had only been informed about the theft of the cash, saying: “They would have been completely and utterly broken if they realised that not only was this individual a cold calculating thief, but that he also deliberately carried out perverted acts in their home which further compromised their fragile health too.
“How could they ever trust a carer again?”