Sounds like your set up is working against you. Can you find a larger space to keep the duck, large enough that you can sit in it on a stool? I had my ducklings in a puppy pen in a bedroom. I could get into the pen with them and just sit and let them get used to me.
Reaching into a cage is a very scary thing from the duck's point of view. First, it is trapped - cornered. So of course it will try to protect itself. And if the cage is on the floor, you are towering above it. Something strange coming in from above is very scary for a duck.