All you can do is bet on how the markets will react to the Federal Reserve's actions or inactions. If you want to bet that one minute after the Fed's meeting, fedfund futures will jump up dramatically, you can go long fedfund futures. If you want to bet that fedfund futures will jump down, you can go short.
Or, if you want to be tricky, you can buy straddles of options-on-futures. You can buy an at-the-money call and simultaneously buy an at-the-money put. This is a bet that the fedfunds futures market will make a large sized move in EITHER direction, up OR down, and if it's big enough, you make money.
If you want to bet that the fedfunds futures market will NOT make a large sized move in either direction, you can sell options straddles (rather than buying them). But this is a tricky play with sophisticated margin requirements and very VERY large risks if things go wrong.