Exophthalmos is a disorder caused by hypersecretion from thyroid?

Exophthalmos. No. This condition is independent of hyper or hypo thyroidism. It is caused by antibodies associated with autoimmune thyroid disease. Theses inflame the eye lining.
Not quite. Graves' disease can cause both high thyroid hormone levels (hyperthyroidism) and bulging eyes (exophthalmos). The cause of both of these manifestations is antibodies that target a person's own proteins. So it's not really correct to say that the high thyroid levels cause the eye problems. While they do both occurs in graves' disease, other causes of hyperthyroidism do not cause the eye problems.