There’s no extension for it, as far as I know. And I believe that we don’t need that kind of thing at all.
Highcharts is quite self-contained. You just have to load a couple of javascript libraries provided by the vendor to use Highcharts.
What we have to do with Yii for it is mainly the server side job of providing the chart data which Hightcharts requires for the initial page loading and for the ajax updating.