There are people today who believe they will find the ark of the covenant somewhere on this earth. Members of the Temple Mount claim to know where it is. If these people were to read Scriptures and believe in God they would learn the Ark of the Covenant was seen in God's Temple in the heavenlies. Therefore, it is not on this earth.
Hebrews 9:1-4 describes the physical House of God -
Now the first covenant had regulations for worship and also an earthly sanctuary. A tabernacle was prepared. In its first room were the lampstand, the table, and the consecrated bread. This was called the Holy Place. Behind the second curtain was a room called the Most Holy Place, containing the golden altar of incense and the gold-covered ark of the covenant. Inside the ark were the gold jar of manna, Aaron’s staff that had budded, and the stone tablets of the covenant.
Revelation 11:19 refers to the spiritual House of God -
Then the temple of God in heaven was opened, and the ark of His covenant appeared in His temple. And there were flashes of lightning, and rumblings, and peals of thunder, and an earthquake, and a great hailstorm.1 Chronicles 15:28
.... all Israel brought up the ark of the covenant of Yahweh with shouting, with the sounding of rams’ horns and trumpets, and with cymbals and the music of harps and lyres.
King David prepared a place for the ark in Jerusalem as the House of God had not been built yet. When Solomon became king, he had his palace and the temple built. When it was finished:
1 Kings 8
Then the priests brought the ark of the covenant of God to its place in the inner sanctuary of the temple, the Most Holy Place, beneath the wings of the cherubim. For the cherubim spread their wings over the place of the ark and overshadowed the ark and its poles. 9-There was nothing in the ark except the two stone tablets that Moses had placed in it at Horeb, where Yahweh had made a covenant with the Israelites after they had come out of the land of Egypt.
The jar of manna and Aaron's staff were no longer present inside the ark. This temple was destroyed during the Siege of Jerusalem by Nebuchadnezzar II of the Babylonian Empire in 587 BC. What I have learned so far is that no remains of the destroyed temple have ever been found.
2 Kings 24:10 -
At that time the servants of Nebuchadnezzar king of Babylon marched up to Jerusalem, and the city came under siege. And Nebuchadnezzar king of Babylon came to the city while his servants were besieging it. Jehoiachin king of Judah, his mother, his servants, his commanders, and his officials all surrendered to the king of Babylon.
So, in the eighth year of his reign, the king of Babylon took him captive. As Yahweh had declared, Nebuchadnezzar also carried off all the treasures from the house of God and the royal palace, and he cut into pieces all the gold articles that Solomon king of Israel had made in the temple .... He carried into exile all Jerusalem—all the commanders and mighty men of valor, all the craftsmen and metalsmiths—ten thousand captives in all. Only the poorest people of the land remained.
Somewhere from the time there is no longer any mention of the ark in Scriptures to this verse in Revelation Yahweh must have removed the ark of the covenant from this earth. A lot of gold treasures are mentioned as being taken to Babylon (Iraq) but there is no specific mention of the ark. No matter who took it or tried to hide it, the Ark of Covenant was seen in His heavenly temple.