CriteriaBuilder builder = sessionFactory.getCurrentSession().getCriteriaBuilder();
CriteriaQuery<String> criteria = builder.createQuery(String.class);
Root<EstimatedObject> root = criteria.from(EstimatedObject.class);

criteria.select(root.get("customer")).distinct(true);

Predicate predicate = builder.like(
        builder.lower(root.get("customer")),
        builder.lower(builder.literal("%" + like + "%"))
        );
criteria.where(predicate);

List<String> customerList = sessionFactory.getCurrentSession().createQuery(criteria).getResultList();

customerList.forEach(System.out::println);

Hibernate: select distinct estimatedo0_.customer as col_0_0_
  from directories_object.estimated_object estimatedo0_
  where lower(estimatedo0_.customer) like lower(?)