You can achieve your requirement with a custom implementation. Basically, you can create a Canvas element with your triangles in it and then on mouse move in the chart you can calculate and change their position. You can see this approach in the attached project.
Please keep in mind that both of the axes of the chart in the attached project are linear. If you use a categorical axis there will be differences in the implementation.
In addition you can take a look at the TrackBall behavior
of the Cartesian chart and see if it won't be suitable for your scenario.
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