The Irish rock band are in New Zealand for the Joshua Tree tour, and are planning a special tribute to Carroll at this weekend's shows at Mt Smart Stadium.
MediaWorks reported the band were seen at the memorial on One Tree Hill, a volcanic peak known in te reo Māori as Maungakiekie.
The band first met Carroll in New Zealand in 1984 during their Unforgettable Fire tour. He charmed his way into a job and became close friends with lead singer Bono.
Carroll was killed in a motorcycle accident in Dublin in 1986, aged 26. U2's song One Tree Hill was penned by Bono and released in 1987 in Carroll's memory.
