You need to have a plot on your chart (like or anything else) so you can connect this indicator to it. I used Cloud's 20 period Conversion line (blue line) as example on the chart.
You can look for divergence on the histogram, that works because most moving averages follow price, they do not lead price. Which means if the distance gets smaller but the trend still continues, it may be a loss of momentum and often a sign for a reversal or pause.
I applied a moving average of the histogram, you can use this to wait for a cross to confirm divergence or can be useful to smooth signals a bit.
Of course you have to play around with it a little and see what works best for you, I have not tested all settings and timeframes.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.