Get product attribute in ui component form magento 2

Try below code:

In your UI form

product_attr_form.xml

<field name="pro_attr">
            <argument name="data" xsi:type="array">
                <item name="options" xsi:type="object">Namespace\ModuleName\Model\Config\Source\Proatr</item>
                <item name="config" xsi:type="array">
                    <item name="label" xsi:type="string" translate="true">Product Attribute List</item>
                    <item name="componentType" xsi:type="string">field</item>
                    <item name="formElement" xsi:type="string">select</item>
                    <item name="component" xsi:type="string">Magento_Ui/js/form/element/ui-select</item>
                    <item name="elementTmpl" xsi:type="string">ui/grid/filters/elements/ui-select</item>
                    <item name="dataScope" xsi:type="string">coupon_code</item>
                    <item name="filterOptions" xsi:type="boolean">false</item>
                    <item name="showCheckbox" xsi:type="boolean">true</item>
                    <item name="chipsEnabled" xsi:type="boolean">true</item>
                    <item name="disableLabel" xsi:type="boolean">true</item>
                    <item name="levelsVisibility" xsi:type="number">1</item>
                    <item name="multiple" xsi:type="boolean">0</item>
                    <item name="sortOrder" xsi:type="number">2</item>
                    <item name="listens" xsi:type="array">
                        <item name="newOption" xsi:type="string">toggleOptionSelected</item>
                    </item>
                    <item name="required" xsi:type="boolean">0</item>
                    <item name="source" xsi:type="string">conditions</item>
                    <item name="validation" xsi:type="array">
                        <item name="required-entry" xsi:type="boolean">true</item>
                    </item>
                </item>
            </argument>
        </field>

Namespace\ModuleName\Model\Config\Source\Proatr

<?php
/**
 * Copyright © 2015 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Namespace\ModuleName\Model\Config\Source;

use Magento\Framework\Data\OptionSourceInterface;

/**
 * Class Coupon
 */
class Proatr implements OptionSourceInterface
{
    protected $_attributeFactory;

    public function __construct (
        \Magento\Catalog\Model\ResourceModel\Product\Attribute\CollectionFactory $attributeFactory
    ) {
        $this->_attributeFactory = $attributeFactory;
    }



    /**
     * Get options
     *
     * @return array
     */
    public function toOptionArray()
    {
        $availableOptions[] = array('value' => 0, 'label' => '--- Please Select ---');
        $attributeInfo = $this->_attributeFactory->create()->addVisibleFilter();

       foreach($attributeInfo as $attributes)
       {
            $attributeId        = $attributes->getAttributeId();
            // You can get all fields of attribute here
            $attrlabel          = $attributes->getFrontendLabel();
            $availableOptions[] = array('value' => $attributeId, 'label' => $attrlabel);
       }
        //echo '<pre>';print_r($availableOptions);die;
        return $availableOptions;   
    }
}

I hope it will help...!!!