The authors differ both on the geographical origin and on the etymology of this surname. E. Rossoni derives it from the medieval place name Cabula, located in the diocese of Sorres, belonging to the Archdiocese of Oristano, in Sardinia. He notes that the Latin term capula designates a small cup, and that in Sardinian capulai or accapuai means "to chop or crush", with probable influence of the Spanish capolar. The surname appears documented in the Peace of Eleonora of 1388. Rossoni also records the variant Capula, peculiar to the Sassari area, specifically of Castelsardo.

V. Blunda, on the other hand, proposes a Sicilian origin and derives the surname from the Greek caboýla, meaning "cloud of dust, mist", an image associated with a cloud of dust or haze that obscures the vision. According to Blunda, the term would have functioned as a nickname applied to the ancestor and would later have become a surname along the family line.

The surname therefore presents at least two independent clusters of origin: one Sardinian, linked to a medieval place name and to Latin and Sardinian roots, and another Sicilian, of Greek base.