CODE EXAMPLE FOR CSHARP

unity check if camera can see object

public static class CameraEx
{
    public static bool IsObjectVisible(this UnityEngine.Camera @this, Renderer renderer)
    {
        return GeometryUtility.TestPlanesAABB(GeometryUtility.CalculateFrustumPlanes(@this), renderer.bounds);
    }
}

// UnityEngine.Camera cam1;
// UnityEngine.Camera cam2;

void Update()
{
    bool isVisibleForCamera1 = cam1.IsObjectVisible(GetComponent<MeshRenderer>());
    bool isVisibleForCamera2 = cam2.IsObjectVisible(GetCoponent<SpriteRenderer>());
}