add_action('woocommerce_edit_account_form', 'codebykp_add_acf_fields_to_account');
function codebykp_add_acf_fields_to_account() {
    $field_value = get_field('custom_field_name', 'user_' . get_current_user_id());
    echo '<p class="form-row form-row-wide">
            <label for="custom_field_name">Custom Field</label>
            <input type="text" class="input-text" name="custom_field_name" id="custom_field_name" value="' . esc_attr($field_value) . '" />
          </p>';
}

add_action('woocommerce_save_account_details', 'codebykp_save_acf_fields_to_account');
function codebykp_save_acf_fields_to_account($user_id) {
    update_field('custom_field_name', $_POST['custom_field_name'], 'user_' . $user_id);
}