The only leading indicator of FF rate

The goal of U.S. monetary policy is maximum employment and price stability.

Federal Reserve policy can directly influence these factors. For example, during the COVID-19 pandemic, employment fell sharply, so policy focused on its recovery, and when inflation runs high as it does now, policy aims to curb it.

However, usually the aim is achieved by stabilizing economic growth.
Therefore, there are many economic indicators that move in tandem with changes in the federal funds rate. (Not that the indicators move in sync by themselves, but that the indicators are moved to align with the FF rate.)

For example, the ISM index. However, until recently, recovery in employment was prioritized, so a divergence has emerged. What can be said now is that, although the economy is recovering rapidly, continuing easy monetary policy may have contributed to inflation as well.

In this way, there are many indicators that move in tandem with changes in the FF rate, but as far as I know, there is only one indicator that tends to lead the movement of the FF rate.