How to return an array using Laravel Eloquent select?

I have this class

<?php

namespace App\Models\Tables;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Query\Builder;
use Illuminate\Support\Facades\DB;

class ZipCode extends Model
{
    protected $table      = 'zip';
    public    $timestamps = false;
    protected $fillable   = [
        'latitude',
        'longitude',
    ];

    public static function radiusSearch($lat, $lng)
    {
        $circle_radius = 3959;
        $subQuery      = '(SELECT *, (' . $circle_radius . ' * acos(cos(radians(' . $lat . ')) * cos(radians(latitude)) * cos(radians(longitude) - radians(' . $lng . ')) + sin(radians(' . $lat . ')) * sin(radians(latitude)))) AS distance FROM zip) AS distances';

        $result = ZipCode::select('*')
            ->from(ZipCode::raw($subQuery))
            ->limit(20);

        var_dump($result);

        return $result;
    }
}

when I call radiusSearch(...) I get a Illuminate\Database\Eloquent\Builder object and not the actual result

$result->get() doesn't work, I get Object of class Illuminate\Database\Eloquent\Builder could not be converted to string

This generic query works just fine ZipCode::where('zip', '11111')->get() just not the above one

Any ideas?

EDIT: the $result returns something like this:

object(Illuminate\Database\Eloquent\Builder)[170]
  protected 'query' => 
    object(Illuminate\Database\Query\Builder)[164]
      public 'connection' => 
        object(Illuminate\Database\MySqlConnection)[166]
          protected 'pdo' => 
            object(PDO)[175]
            ...
  protected 'model' => 
    object(App\Models\Tables\ZipCode)[171]
      protected 'table' => string 'zip' (length=9)
      public 'timestamps' => boolean false
      ...

If I do $result->getModel()->get()->toArray() this returns all results from the table