Unity provides standard Spline asset https://docs.unity3d.com/Packages/com.unity.splines@2.1/manual/getting-started-with-splines.html

Use BGCurve only if standard Spline asset does not provide required feature

BGCurve

Bezier curve editor for Unity game engine

Unity Asset store: https://www.assetstore.unity3d.com/en/#!/content/59043

Docs: http://www.bansheegz.com/BGCurve/

Video (click to view on youtube):