Smoke Monster
I believe that the smoke monster is released when the H-bomb explodes and the electromagnetic force was a prison that was built for the smoke monster that it could not escape from.
It is a creature that learns from people and simulates sounds it has heard which could be the sound of the machinery and drilling when they were digging in the ground or the sounds of the metalic crane being pulled down and the chains by the electromagnetic force. I think the whispers may also come from the smoke monster.
Because Juliette was the closest to the electomagnetic force and the explosion I think smokie will absorb her consciousness/memories as well as the noises Julliette heard above as it is released.
That’s as far as I’ve got with this but please let me know your thoughts.
That would explain the noises. I always wondered why a pillar of smoke would sound like bending girders and clanking chains. But, why does it live in that ancient temple?