Add new user meta fields for learndash dashboard profile

add_filter( 'ld_dashboard_user_profile_fields', 'add_custom_profile_fields' );

// Add custom field in the profile settings form.
function add_custom_profile_fields($profile_fields) {
    $profile_fields['user_url']        = array(
                'title' => esc_html__( 'Custom Field', 'ld-dashboard' ),
                'tag'   => 'input',
                'type'  => 'text',
                'name'  => 'custom_field',
                'value' => get_user_meta( $current_user->ID, 'custom_field', true ),
                'class' => 'form-url',
            )
    return $profile_fields;
}

add_action( 'ld_dashboard_save_user_profile_fields', 'update_custom_meta_field' );

// Save custom field data.
function update_custom_meta_field() {
    if ( isset( $_POST['custom_field'] ) && '' != $_POST['custom_field'] ) {
            update_user_meta( $current_user->ID, 'custom_field', sanitize_text_field( wp_unslash( $_POST['custom_field'] ) ) );
    } else {
        update_user_meta( $current_user->ID, 'custom_field', '' );
    }