I think I have created the best version of an Ender 3 bed leveler. This utilizes a Harbor Freight digital dial indicator. I've tried the BL Touch, the BIQU Microprobe; none of them can compete with my method.So there are two versions.
1) The tested version that I am currently using (blue).
2) Untested version which should allow you to rotate the dial indicator out of the way (orange).

How to proceed:
You'll need to print whichev version that you choose.
You'll take the upper left (facing extruder) bolt that holds the roller, apart.
Press the spacer into the printed part. I used a vice but pliers would do the job. It's a snug fit but nothing that a little force can't overcome.
Re-assemble the bolt with the roller.
The HF dial indicator will now slide into the printed part and attach using a 1/4"x20 bolt.
If you printed the tested version, you will need something to hold the probe up while printing. I am currently using a hair clip that my wife uses on her shih-tzu pup as shown in the photo.
The pivot one should allow you to rotate the dial indicator so that it doesn't hit the bed when not in use.
Yes, the design is intended to leave the dial indicator in place even while printing.

In Marlin, you'll need to have a few things enabled.
In Config.h
Uncomment "PROBE_MANUALLY"
Uncomment "MESH_BED_LEVELING"
Uncomment "LCD_BED_LEVELING"

In Config.adv.h
THIS IS THE IMPORTANT PART!! THIS IS WHAT ALLOWS THE DIAL INDICATOR TO PROBE RELEVANT SPOTS!
if EITHER(MESH_BED_LEVELING, AUTO_BED_LEVELING_UBL)
Override the mesh area if the automatic (max) area is too large
define MESH_MIN_X 45
define MESH_MIN_Y 30
define MESH_MAX_X 235
define MESH_MAX_Y 220
endif

Adjust the above numbers to suit your needs.

So if you're still following along then you have:
1) Printed the part.
2) Mounted the part.
3) Made the adjustments in Marlin.
Now you're simply needing to bed level and adjust the z.

I've set the probe points to 4x4 (16) but doing more or less is an option

=MESH=
define GRID_MAX_POINTS_X 4 Don't use more than 7 points per axis, implementation limited.

So yea, once this is all set up, you should be able to do the bed/paper/nozzle offset and from there zero your indicator. From that point on, just adjust your z, using the LCD, where you are as close to 0.00 as possible.
I have gotten awesome results with this method

:)