English Standard Version (ESV)
When we have people over for dinner, there's always a random room in which a number of things get placed, in the effort to make the house look tidier than perhaps it usually is. The hope is that the guests will never discover this room.
Here, the Psalmist is expressing a tremendous amount of trust in God -- he's inviting God to explore all the extra rooms where the hidden things are placed, in the hopes of finding all those wayward thoughts so that they can be covered with grace, all because the Psalmist's goal is to be led in the way everlasting.
Friends, we can trust God with all the secrets of our lives, even the darkest ones we try to hide. May they be uncovered before the light of God's love, bathed in his mercy, and healed, that they may no longer hinder our progress on the way everlasting.