A black hole with the mass of Earth out of sync with it surroundings will surely emit a lot on UV and X-rays. Space isn't completely empty, and the stuff on its path won't orbite it.

We would detect one entering our Solar System.

the fast moving mass of earth will distort orbits via gravity. that will be noticed

Hmmm, that's not what happened in the Seveneves I read... The reason for the moons destruction was never mentioned iirc. The 'Agent' was never revealed.

Good yarn though.

Well, do you know how we "see" black holes? The "body" of a black hole is nothing but darkness, but we see the radiation given off by the mass accelerating toward the black hole event horizon that can often reach significant fractions of c. Given the high mass density of a planet compared to space, a massive amount of hard radiation will be released.

Also the relative velocities of earth and the black hole is extremely important. Depending on the relative velocities, it's possible that the blackhole simply gets lodged in the earth's core and we're 100% dead, another 100% dead scenario is if it plunges in, out the other side, but then "falls back" for another pass and so on.

Won't it pull some of the matter it passes through under the event horizon? The extremely curved spacetime will likely turn rock to dust in near vicinity. Then, as the mass grows, so would the gravitational pull, while the speed relative to the planet being punctured would lower due to conservation of momentum.

If the tiny bullet-class black hole makes it through a planet, it could gain significant additional mass, and leave quite an exit wound.

Maybe ...

Earth by Brin

Hyperion Cantos by Simmons

Ilium by Simmons

Doomsday Effect by Thomas Wren

If I thought for a few more minutes I could probably come up with a half dozen examples (or expanded the definition to include eating the moon or mars, or included ones where it would be a massive spoiler)...

A gravitationally captured/trapped black hole eating earth is relatively common plot device in science fiction.

Sounds familiar, could that be the Big Mistake in Hyperion or the Hole Man short story? https://en.wikipedia.org/wiki/The_Hole_Man https://hyperioncantos.fandom.com/wiki/Big_Mistake

Plenty of titles at https://en.wikipedia.org/wiki/Black_holes_in_fiction

Do you remember its name?

If it's not moving quickly, we would notice its gravitational interaction with the well-known dynamics of the various large objects already in our solar system. A 9mm black hole's gravitational influence would be fairly subtle though compared to a multiple Earth-mass black hole; the bowling ball sized black hole mentioned in the paper as an upper bound is not the kind of thing that could wander into the inner solar system unnoticed.

Pretty big plot point! Don't want to give away the story