Paste the below code in pine editor and save it, apply on chart and you will get a arrow highlighting the day high volume on an Intraday chart, you can hide this on a daily timeframe chart.
//@version=4
study(title="Highest Volume of the Day Signal", shorttitle="HVOD", overlay=true)
var float highestVolume = na
var bool isHighestVolume = na
if (dayofweek != dayofweek[1])
highestVolume := volume
else if (volume > highestVolume)
highestVolume := volume
isHighestVolume := volume == highestVolume
// Plot a signal on the chart, but only when not on the daily timeframe
plotshape(series=isHighestVolume and timeframe.isintraday, title="Highest Volume", location=location.belowbar, color=color.green, style=shape.triangleup, size=size.small)