Is it possible to detect when a player is near a brick or when a brick is near another brick?

Yes you could use magnitude here an example.

player = game.Players.LocalPlayer  --define player
part1 = game.Workspace.Part1 --the part you want to use to detect the player

while true do -- use a while loop to constantly check if the player is close
    wait()
    if(player.Character.Torso.Position - part1.Position).magnitude <=5 then -- this line takes your characters position and subtracts it from the parts position ad check to see if it is less than or equal to
        print("You are near me") -- prints when you are close enough to the part
    end
end

--to detect two bricks same concept instead of adding player just add  another part to the script
so it would look like this 

part1 = game.Workspace.Part1
part2 = game.Workspace.Part2

while true do 
    wait()
    if(part1.Position - part2.Position).magnitude <=5 then
        print("You are near me") 
    end
end

I hope this helps.