Its hard to say, comic Cap could probably throw his proto-vibranium shield and fuck MCU Ultron's whole world.

But the point of Captain America is not that this move would harm Ultron. The point is Cap would choke a robot to hold it off for even one more second as it tried to harm others, and he did just that. And that's true no matter what version of Captain America we are talking about, except maybe not Captain Hydra while he is brainwashed.