Oh do I know what you are going thru. Cobalt, my little sweetheart was terrified of everything when I first got him. You COULD NOT catch him even if his life depended on it.
This problem lasted about 1 month as soon as I moved him to the barn. He had never seen a stable, new people, new horses and because of how young he was at the time, he hadn't been played with a whole lot.
I left a halter 24/7 for about a month while I worked on his catching. For some time you couldn't even get near him as he would run away. I had to bribe his best pasture buddy at which point he would stay nearby just never close enough for me to reach. With time he slowly got closer and I would be able to sneak my arm under his buddy's neck and grab onto his halter.
Me doing this always worried him quite a bit but he never pulled back. I would grab him and his best buddy and I would take them outside the pasture, tie them and feed them supplements which to them was a huge treat. It took a few days of doing so before he realised that being caught wasnt all that bad because it meant he would get food. I NEVER fed him IN the field, EVER. He would get feed only once caught and tied outside the pasture. With time it came down to just taking him out of the pasture.
He eventually started to expect it every day and would come and wait for me at the gate. He never got nosy and never searched for food as he got into the habit of when and where he got his food. I was able to eventually remove his halter once back in pasture. As you bring him and tie him outside the pasture include a good grooming but only whats pleasant to that horse. As time evolves start to remove the feeding and only groom.
I did so for about 1-2 months. During that time I build a bond with him and worked with him on the ground, showed him things and he learned things were ok.
Now he adores being worked with and will come and wait at the gate when he sees my car come up. Excellent boy. I never feed him or give him treats when I catch him so he never looks for them and I seldomly feed him supplements now so he knows not to ask for them or he gets in trouble. He LOVES being played with. Brushing, talking to him, anything, he LOVES it all.