How to get values from dropdownlist, radiolist and checkbox list

Helli i have simple form, which inserting data in my table, the problem is that i don't know how to: 1)get String value of selected dropdownlist item; 2)get String value of selected radio element 3)get smthng like String arrray of selected checkboxes; Here is the form

<?php $form = ActiveForm::begin(); ?>

        <?= $form->field($model, 'first_name') ?>
        <?= $form->field($model, 'last_name') ?>
        <?= $form->field($model, 'gender')->radioList([
            1 => 'Male',
            2 => 'Female'
        ]) ?>
        <?= $form->field($model, 'faculty')->dropdownList([
            1 => 'Faculty of Information Technology',
            2 => 'Faculty of Math Science',
            3 => 'Faculty of Ukrainian Literature',
            4 => 'Faculty of Health'
        ]) ?>
        <?= $form->field($model, 'languages')->checkboxList([
            1 => 'Java',
            2 => 'C++',
            3 => 'C#',
            4 => 'Python',
            5 => 'PHP',
            6 => 'Java Script'
        ]) ?>

        <div class="form-group">
            <?= Html::submitButton('Submit', ['class' => 'btn btn-primary']) ?>
        </div>
    <?php ActiveForm::end(); ?>

ActiveRecord class

class Users extends \yii\db\ActiveRecord
{
    /**
     * @inheritdoc
     */
    public static function tableName()
    {
        return 'users';
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            [['first_name', 'last_name', 'gender', 'faculty', 'languages'], 'required'],
            [['first_name', 'last_name'], 'string', 'max' => 15],
            [['gender'], 'string', 'max' => 7],
            [['faculty'], 'string', 'max' => 20],
            [['languages'], 'string', 'max' => 50],
        ];
    }

    /**
     * @inheritdoc
     */
    public function attributeLabels()
    {
        return [
            'first_name' => 'First Name',
            'last_name' => 'Last Name',
            'gender' => 'Gender',
            'faculty' => 'Faculty',
            'languages' => 'Programming Languages',
        ];
    }

    public static function primaryKey()
    {
        return ['customer_id','group_id'];
    }
}

So problem is that values that inserted in db after form accepted is indexes of selected values, but i need values