What method is used for detecting
Like @Daniel Sumner mentioned non-verbal techniques like maintaining eye contact, telling offenders to remember events in reverse order are used to detect deception.
Polygraph test is useful, but trained people can easily beat it. It also generate false positive results. So, it is not reliable.
A variety of methods, although the polygraph may be used it cannot be used as evidence within a court.
Other methods such as non-verbal communication may also be used but to mixed results.
Generally, some of the most reliable methods involve cognitive interviews in which evidence is suppressed until a suspect has talked themselves into a hole of sorts.
Other methods such as linguistic clues may also be used.
The problem with many methods is not so much that they are low in catching lies, but they may falsly implicate honest people as liars. This false positive reate has to come down before many of these methods can be reliably used.