This formula:

=OR(ISNUMBER(-MID(A1,ROW(INDIRECT("1:"&LEN(A1))),1)))

Say you have some stuff in A1, for example:  asd123

the row(indirect()) resolves to this array:
{1;2;3;4;5;6}

Then the mid(a1,{1;2;3;4;5;6},1) is gonna just look at each of the characters in
that cell:
a, then s, then d, then 1, 2, 3

The hyphen in front of the mid (-mid()) converts anything that looks like a
number to a number.  There's a difference between '1 and 1 (note the apostrophe
making the first text).  And =mid() always returns text.

The isnumber() will look at the innards of that expression and return an array
that looks like:
{FALSE;FALSE;FALSE;TRUE;TRUE;TRUE}

The =or() will return TRUE if there's at least one TRUE.  Else it'll return
FALSE.

Be careful, though.  You still have to array enter it (ctrl-shift-enter).