The measurements are not part of the open source CesiumJS. They are available on Cesium ion, using Cesium Stories (see https://cesium.com/docs/tutorials/stories-introduction/). So if you just need to make some distance/height/area measurements, you can upload your data to Cesium ion and use it there.
Is it possible to add the Measure tool to my app’s Cesium implementation? It seems like I should be able to create the measure widget pretty easily like this
var measureWidget = new Cesium.Measure({
container : 'measureContainer',
scene : scene,
units : new Cesium.MeasureUnits({
distanceUnits : Cesium.DistanceUnits.METERS,
areaUnits : Cesium.AreaUnits.SQUARE_METERS,
volumeUnits : Cesium.VolumeUnits.CUBIC_FEET,
angleUnits : Cesium.AngleUnits.DEGREES,
slopeUnits : Cesium.AngleUnits.GRADE
})
});