magento 2 backend custom form
<?xml version="1.0" encoding="UTF-8"?>
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
<argument name="data" xsi:type="array">
<item name="js_config" xsi:type="array">
<item name="provider" xsi:type="string">employee_form.employee_form_data_source</item>
<item name="deps" xsi:type="string">employee_form.employee_form_data_source</item>
</item>
<item name="label" xsi:type="string" translate="true">Employee Information</item>
<item name="config" xsi:type="array">
<item name="dataScope" xsi:type="string">data</item>
<item name="namespace" xsi:type="string">employee_form</item>
</item>
<item name="template" xsi:type="string">templates/form/collapsible</item>
</argument>
<dataSource name="employee_form_data_source">
<argument name="dataProvider" xsi:type="configurableObject">
<argument name="class" xsi:type="string">Namespace\Modulename\Model\DataProvider</argument>
<argument name="name" xsi:type="string">employee_form_data_source</argument>
<argument name="primaryFieldName" xsi:type="string">id</argument>
<argument name="requestFieldName" xsi:type="string">id</argument>
</argument>
<argument name="data" xsi:type="array">
<item name="js_config" xsi:type="array">
<item name="component" xsi:type="string">Magento_Ui/js/form/provider</item>
</item>
</argument>
</dataSource>
<fieldset name="employee_details">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="collapsible" xsi:type="boolean">true</item>
<item name="label" xsi:type="string" translate="true">Employee Details</item>
<item name="sortOrder" xsi:type="number">20</item>
</item>
</argument>
<field name="employee_id">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="dataType" xsi:type="string">text</item>
<item name="label" xsi:type="string" translate="true">Employee Id</item>
<item name="formElement" xsi:type="string">input</item>
<item name="source" xsi:type="string">employee</item>
<item name="dataScope" xsi:type="string">employee_id</item>
</item>
</argument>
</field>
<field name="employee_name">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="dataType" xsi:type="string">text</item>
<item name="label" xsi:type="string" translate="true">Employee Name</item>
<item name="formElement" xsi:type="string">input</item>
<item name="source" xsi:type="string">employee</item>
<item name="dataScope" xsi:type="string">employee_name</item>
</item>
</argument>
</field>
<field name="employee_salary">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="dataType" xsi:type="string">text</item>
<item name="label" xsi:type="string" translate="true">Employee Salary</item>
<item name="formElement" xsi:type="string">input</item>
<item name="source" xsi:type="string">employee</item>
<item name="dataScope" xsi:type="string">employee_salary</item>
</item>
</argument>
</field>
<field name="employee_address">
<argument name="data" xsi:type="array">
<item name="config" xsi:type="array">
<item name="dataType" xsi:type="string">text</item>
<item name="label" xsi:type="string" translate="true">Employee Address</item>
<item name="formElement" xsi:type="string">textarea</item>
<item name="source" xsi:type="string">employee</item>
<item name="dataScope" xsi:type="string">employee_address</item>
</item>
</argument>
</field>
</fieldset>
</form>