Question

an instrument used to measure the direction of wind is​

Answer 1

an instrument used to measure the direction of wind is wind vane

Answer 2

$\huge\color{blue}{anemometer}$

An anemometer is a type of weather instrument that measures wind speed. Some of these instruments measure both wind speed and wind direction.  Anemometers are common at weather stations.  A cup anemometer is a type of instrument that uses three or four hemispherical cups mounted on horizontal arms on a vertical rod. The wind pushes the cups and causes the arms to rotate at a rate proportional to the wind speed.