From Halopedia, the Halo wiki
United Nations Space Command
UNSC Marine Corps
Cayman Squad is a squad of UNSC Marines who fought in the Installation 07 conflict. Around the time John-117 arrived on the fragmented section of Zeta Halo, Banished forces attacked Cayman Squad. The Chief's AI companion, The Weapon, picked up Cayman's distress call, prompting the Spartan to aid the marines.
In Halo Infinite, Cayman Squad is found in the "Lockdown" section of the campaign. Answering their distress call earns the player 30 Valor points. This valor is awarded even if all members of Cayman Squad are killed.