A security company that worked with the team on their 2009 tour of South Africa and 2013 tour in Australia carry out the checks, Lions chief executive John Feehan said.
"They are experts in electronic surveillance, to ensure that we are not being looked at or listened to," Feehan told Britain's Daily Telegraph newspaper.
"The team room, for example, is swept regularly and no one is allowed in there unless they are part of the squad, and if there is any suspicion at all they will do another sweep," he said.
"Nothing is perfect in this life and if someone is determined enough they probably will get something, but all we can do is try to ensure that they don't."
The Lions face the All Blacks at Eden Park in Auckland on Saturday in the first of three tests.
International rugby teams have become increasingly security conscious in modern times and routinely hired consultants to not only ensure the team is safe on their tours, but also to stop the opposition discovering tactics.
The All Blacks have been targeted in the past when in 2013 a British newspaper reporter gained access to the team room in their hotel and revealed some of the planning and motivational messages written on a whiteboard.
All Blacks coach Steve Hansen has also accused members of the foreign media of covertly filming their practice sessions and at the last Rugby World Cup in England, the team trained behind a four-metre fence.
The All Blacks have also become embroiled in a bugging scandal of their own when a listening device was discovered in their hotel in Sydney last year before they played the Wallabies.
New South Wales Police conducted an investigation and have charged a security consultant regularly used by the All Blacks with one count of false misrepresentation.