Outdated link to debfiles removed, use package from unstable-repo instead.
$ hashcat -b
hashcat (v4.0.0) starting in benchmark mode...
Benchmarking uses hand-optimized kernel code by default.
You can use it in your cracking session by setting the -O option.
Note: Using optimized kernel code limits the maximum supported password length.
To disable the optimized kernel code in benchmark mode, use the -w option.
clGetPlatformIDs(): CL_INVALID_VALUE
Started: Wed Apr 25 19:03:46 2018
Stopped: Wed Apr 25 19:03:46 2018
clGetPlatformIDs(): CL_INVALID_VALUE
hashcat is incompatible with your device.
How to fix it?
hashcat v.4.0.0
device = aarch64

Edit: benchmark testing show same problems
@vida1j No idea. On some devices it works on others not, it even depends on Android version. OpenCL version of hashcat is totally unsupported in Termux at this time.
Just try install another tools like CMSmap for good hashing..

I don't know which version you are trying to use but:
pkg upgrade.unstable-repo.Is there any way to fix the error:

Type
Pkg install unstable-repo
After that
Pkg install hashcat

Most helpful comment
Outdated link to debfiles removed, use package from
unstable-repoinstead.