{{ form_start(searchForm) }}
<div class="input-group w-100">
    {{ form_widget(searchForm.search) }}
    <div class="input-group-prepend">
        <button class="btn btn-secondary">
            <i class="icone icon-magnifier"></i>
        </button>
    </div>
    {{ form_widget(searchForm.search) }}
</div>
{{ form_end(searchForm) }}