public Task<SurfaceZsResult> GetZsFromSurfaceAsync( 
   Geometry geometry
)

{
    //Note: This method must be called on the MCT
    // Get the center of the map's full extent
    MapPoint mapPoint = MapView.Active.Map.CalculateFullExtent().Center;
    //Pass any Geometry type to GetZsFromSurfaceAsync
    var surfaceZResult = await MapView.Active.Map.GetZsFromSurfaceAsync(mapPoint);
    if (surfaceZResult.Status == SurfaceZsResultStatus.Ok)
    {
        // cast to a mapPoint
        var mapPointZ = surfaceZResult.Geometry as MapPoint;
        var z = mapPointZ.Z;
    }
}

{
    var eleLayer = MapView.Active.Map.GetElevationSurfaceLayers().FirstOrDefault(l => l.Name == "TIN");
    //Pass any Geometry type to GetZsFromSurfaceAsync
    //Note: This method must be called on the MCT
    //Ensure the feature layer is a line layer and is Z aware
    var selectedFeatures = featureLayer.GetSelection();
    var rowCursor = selectedFeatures.Search();
    while (rowCursor.MoveNext())
    {
        var feature = rowCursor.Current as Feature;
        var polyline = feature.GetShape() as Polyline;
        var zResult = await MapView.Active.Map.GetZsFromSurfaceAsync(polyline, eleLayer);
        if (zResult.Status == SurfaceZsResultStatus.Ok)
        {
            var polylineZ = zResult.Geometry as Polyline;
            // process the polylineZ
            // For example, you can iterate through the points and access their Z values
        }
    }
}