Kaaba is the Qibla i.e. the direction Muslims face during their prayers. It is important to note that though Muslims face the Kaaba during prayers, they do not worship the Kaaba. Muslims worship and bow to none but Allah.
It is mentioned in Surah Baqarah: “We see the turning of thy face (for guidance) to the heavens: now shall We turn thee to a Qiblah that shall please thee. Turn then thy face in the direction of the Sacred Mosque: wherever ye are, turn your faces in that direction.” [Al-Qur’an 2:144]