//First option
add_action( 'woocommerce_before_cart', 'woocommerce_checkout_login_form', 10 );

//Second option
add_action( 'woocommerce_before_cart', 'function custom_checkout_login_form', 10 );
function custom_checkout_login_form() {
?>
<div class="woocommerce-form-login-toggle">
    <?php wc_print_notice( apply_filters( 'woocommerce_login_form', __( 'Returning customer?', 'woocommerce' ) ) . ' <a href="#" class="showlogin">' . __( 'Click here to login', 'woocommerce' ) . '</a>', 'notice' ); ?>
</div>
<?php

woocommerce_login_form(
    array(
        'message'  => __( 'If you have shopped with us before, please enter your details below. If you are a new customer, please proceed to the Billing & Shipping section.', 'woocommerce' ),
        'redirect' => wc_get_page_permalink( 'checkout' ),
        'hidden'   => true,
    )
);}