I have iron def anaemia. colonoscopy result ok, fobt +ve for blood am waiting for capsule endoscopy result. what maybe causes for microscopic bleeding?

Many possibilities: Anything from a big ulcer to several little ulcers (do you take oral painkillers?) to angiodysplasia of the colon (it's subtle) to a stomach tumor to reflux esophagitis to -- yes, hookworm still is out there. The fobt may be a red herring and blood loss may be in the urine. Your diet's iron-rich, correct? I hope you find the cause, and that it's something easy to treat.

EGD a start : First check the basic tests is done, from CBC w ptt, itibcl ferritin, and a iron-tracer ct scan will pin point the sourse of bleeding.